Spongilla plumosa, Carter, J. Bomb. Asiat. Soc. iii, p. 34, pl. i, fig. 2, & Ann. Nat. Hist. (2) iv, p. 85, pl. iii, fig. 2 (1849).Spongilla plumosa, Bowerbank, P. Zool. Soc. London, 1863, p. 449, pl. xxxviii, fig. 5.Dosilia plumosa, J. E. Gray,ibid.1867, p. 551.Meyenia plumosa, Carter, Ann. Nat. Hist. (5) vii, p. 94, pl. v, fig. 6 (1881).Meyenia plumosa, Potts, P. Ac. Philad. 1887, p. 233.Ephydatia plumosa, Weltner, Arch. Naturg. lxi (i), p. 126 (1895).Ephydatia plumosa, Petr, Rozp. Ceske Ak. Praze, Trída ii, pl. ii, figs. 29, 30 (text in Czech) (1899).
Spongeforming soft irregular masses which are sometimes as much as 14 cm. in diameter, of a pale brown or brilliant green colour; no branches developed but the surface covered with irregular projections usually of a lobe-like nature.
Skeletondelicate, with the branches diverging widely, exhibiting the characteristic structure of the genus in a marked degree, containing a considerable amount of chitin, which renders it resistant in spite of its delicacy.
Spicules.Skeleton-spicules smooth, sharply pointed, nearly straight, moderately slender, about twenty times as long as their greatest transverse diameter. Flesh-spicules occasionally amphioxous or birotulate and with a single shaft, more frequently consisting of many shafts meeting in a distinct central nodule, which is itself smooth; the shafts irregularly spiny, usually more or less nodular at the tip, which often bears a distinct circle of recurved spines that give it a rotulate appearance. Gemmule-spicules with long, slender, straight shafts, which bear short, slender, straight, horizontal spines sparsely and irregularly scattered over their surface; the rotulæ distinctly convex when seen in profile; their edge irregularly and by no means deeply notched; the shafts not extending beyond their surface but clearly seen from above as circular umbones.
Illustration: Fig. 22.—Dosilia plumosa.Fig. 22.—Dosilia plumosa.
Fig. 22.—Dosilia plumosa.
A=microscleres, × 240; B=gemmule as seen in optical section from below, × 75. (From Rambha.)
Gemmules.Somewhat depressed, covered with a thick granular pneumatic coat, in which the spicules stand erect; the single aperture depressed. Each gemmule surrounded more or less distinctly by a circle or several circles of flesh-spicules.
Typein the British Museum; some fragments in the Indian Museum.
Geographical Distribution.—Bombay and Madras. Carter's specimens were taken in the island of Bombay, mine at Rambha in the north-east of the Madras Presidency. I have been unable to discover this species in the neighbourhood of Calcutta, but it is apparently rare wherever it occurs.
Biology.—Carter writes as regards this species:—"This is the coarsest and most resistant of all the species. As yet I have only found three or four specimens of it, and these only in two tanks.I have never seen it fixed on any solid body, but always floating on the surface of the water, about a month after the first heavy rains of the S.W. monsoon have fallen. Having made its appearance in that position, and having remained there for upwards of a month, it then sinks to the bottom. That it grows like the rest, adherent to the sides of the tank, must be inferred from the first specimen which I found (which exceeds two feet in circumference) having had a free and a fixed surface, the latter coloured by the red gravel on which it had grown. I have noticed it growing, for two successive years in the month of July, on the surface of the water of one of the two tanks in which I have found it, and would account for its temporary appearance in that position, in the following way, viz., that soon after the first rains have fallen, and the tanks have become filled, all the sponges in them appear to undergo a partial state of putrescency, during which gas is generated in them, and accumulates in globules in their structure, through which it must burst, or tear them from their attachments and force them to the surface of the water. Since then the coarse structure ofplumosawould appear to offer greater resistance to the escape of this air, than that of any of the other species, it is probable that this is the reason of my having hitherto only found it in the position mentioned."
It seems to me more probable that the sponges are actually broken away from their supports by the violence of the rain and retain air mechanically in their cavities. The only specimens ofD. plumosathat I have seen alive were attached very loosely to their support. In writing of the "coarse structure" of this species, Carter evidently alludes to the wide interspaces between the component branches of the skeleton.
My specimens were attached to the stem of a water-lily growing in a pool of slightly brackish water and were of a brilliant green colour. I mistook them at first for specimens ofS. lacustrissubsp.reticulatain which the branches had not developed normally. They were taken in March and were full of gemmules. The pool in which they were growing had already begun to dry up.
Genus 5.TROCHOSPONGILLA,Vejdovsky.
Trochospongilla, Vejdovsky, Abh. K. Böhm. Ges. Wiss. xii, p. 31 (1883).Trochospongilla, Wierzejski, Arch. Slaves de Biologie, i, p. 44 (1886).Trochospongilla, Vejdovsky, P. Ac. Philad. 1887, p. 176.Meyenia, Potts (partim),ibid.p. 210.Tubella,id.(partim),ibid., p. 248.Meyenia, Carter (partim), Ann. Nat. Hist. (5) vii, p. 90 (1881).Trochospongilla, Weltner, in Zacharias's Tier- und Pflanzenwelt, i, p. 215 (1891).Trochospongilla,id., Arch. Naturg. lxi (i), p. 120 (1895).Tubella,id.(partim),ibid.p. 128.
Type,Spongilla erinaceus, Ehrenberg.
The characteristic feature of this genus is that the rotulæ of the gemmule-spicules, which are homogeneous, have smooth instead of serrated edges. Their stem is always short and they are usually embedded in a granular pneumatic coat. The sponge is small in most of the species as yet known; in some species microscleres without rotulæ are associated with the gemmules.
Illustration: Fig. 23.—A=skeleton-spicule of Trochospongilla latouchiana; A'=gemmule-spicule of the same species; B=gemmule of T. phillottiana as seen in optical section from above; B'=skeleton-spicule of same species: A, A', B' × 240; B × 75. All specimens from Calcutta.Fig. 23.—A=skeleton-spicule ofTrochospongilla latouchiana; A'=gemmule-spicule of the same species; B=gemmule ofT. phillottianaas seen in optical section from above; B'=skeleton-spicule of same species: A, A', B' × 240; B × 75. All specimens from Calcutta.
Fig. 23.—A=skeleton-spicule ofTrochospongilla latouchiana; A'=gemmule-spicule of the same species; B=gemmule ofT. phillottianaas seen in optical section from above; B'=skeleton-spicule of same species: A, A', B' × 240; B × 75. All specimens from Calcutta.
I think it best to include in this genus, as the original diagnosis would suggest, all those species in which all the gemmule-spicules are definitely birotulate and have smooth edges to their disks, confining the nameTubellato those in which the upper rotula is reduced to a mere knob. Even in those species in which the two disks are normally equal, individual spicules may be found in which the equality is only approximate, while, on the other hand, it is by no means uncommon for individual spicules in such species as"Tubella" pennsylvanica, which is here included inTrochospongilla, to have the two disks nearly equal, although normally the upper one is much smaller than the lower. There is very rarely any difficulty, however, in seeing at a glance whether the edge of the disk is smooth or serrated, the only species in which this difficulty would arise being, so far as I am aware, the AustralianEphydatia capewelli* (Haswell), the disks of which are undulated and nodulose rather than serrated.
Geographical Distribution.—The genus includes so large a proportion of small, inconspicuous species that its distribution is probably known but imperfectly. It would seem to have its headquarters in N. America but also occurs in Europe and Asia. In India three species have been found, one of which (T. pennsylvanica) has an extraordinarily wide and apparently discontinuous range, being common in N. America, and having been found in the west of Ireland, the Inner Hebrides, and near the west coast of S. India. The other two Indian species are apparently of not uncommon occurrence in eastern India and Burma.
Key to the Indian Species ofTrochospongilla.
18.Trochospongilla latouchiana*,Annandale.
Trochospongilla latouchiana, Annandale, J. Asiat. Soc. Bengal, 1907, p. 21, fig. 5.Trochospongilla latouchiana,id., Rec. Ind. Mus. ii, p. 157 (1908).Trochospongilla leidyi,id.(necBowerbank),ibid.iii, p. 103 (1909).
Illustration: Fig. 24.—Trochospongilla latouchiana.Fig. 24.—Trochospongilla latouchiana.
Fig. 24.—Trochospongilla latouchiana.
Vertical section of part of skeleton with gemmulesin situ, × 30; also a single gemmule, × 70. (From Calcutta).
Spongeforming cushion-shaped masses rarely more than a few centimetres in diameter or thickness and of a brown or yellow colour, hard but rather brittle; surface evenly rounded, minutely hispid; oscula inconspicuous, small, circular, depressed, very few in number; external membrane adhering closely to the parenchyma;a chitinous membrane at the base of the sponge. Larger sponges divided into several layers by similar membranes.
Skeletondense, forming a close reticulation; radiating fibres slender but quite distinct, running up right through the sponge, crossed at frequent intervals by single spicules or groups of spicules.
Spicules.Skeleton-spicules smooth, about twenty times as long as the greatest transverse diameter, as a rule sharply pointed; smooth amphistrongyli, which are often inflated in the middle, sometimes mixed with them but never in large numbers. No flesh-spicules. Gemmule-spicules with the rotulæ circular or slightly asymmetrical, flat or nearly flat, marked with a distinct double circle as seen from above, sometimes not quite equal; the shaft not projecting beyond them; the diameter of the rotule 4-1/2 to 5 times that of the shaft, which is about 2-2/3 times as long as broad.
Gemmulessmall (0.2 × 0.18 mm.), as a rule very numerous and scattered throughout the sponge, flask-shaped, clothed when mature with a thin microcell coat in which the birotulates are arranged with overlapping rotulæ, their outer rotulæ level with the surface; foraminal aperture circular, situated on an eminence.
Average Measurements.
T. latouchianais closely related toT. leidyi(Bowerbank) from N. America, but is distinguished by its much more slender skeleton-spicules, by the fact that the gemmules are not enclosed in cages of megascleres or confined to the base of the sponge, and by differences in the structure of the skeleton.
Typein the Indian Museum.
Geographical Distribution.—Lower Bengal and Lower Burma.Localities:—Bengal, Calcutta and neighbourhood (Annandale):Burma, Kawkareik, Amherst district, Tenasserim (Annandale).
Biology.—This species, which is common in the Museum tank, Calcutta, is apparently one of those that can grow at any time of year, provided that it is well covered with water. LikeT. leidyiit is capable of producing fresh layers of living sponge on the top of old ones, from which they are separated by a chitinous membrane. These layers are not, however, necessarily produced in different seasons, for it is often clear from the nature of the object to which the sponge is attached that they must all have been produced in a short space of time. What appears to happen in most cases is this:—A young sponge grows on a brick, the stem of a reed or some other object at or near the edgeof a pond, the water in which commences to dry up. As the sponge becomes desiccated its cells perish. Its gemmules are, however, retained in the close-meshed skeleton, which persists without change of form. A heavy shower of rain then falls, and the water rises again over the dried sponge. The gemmules germinate immediately and their contents spread out over the old skeleton, secrete a chitinous membrane and begin to build up a new sponge. The process may be repeated several times at the change of the seasons or even during the hot weather, or after a "break in the rains." If, however, the dried sponge remains exposed to wind and rain for more than a few months, it begins to disintegrate and its gemmules are carried away to other places. Owing to their thin pneumatic coat and relatively heavy spicules they are not very buoyant. Even in the most favourable circumstances the sponge ofT. latouchiananever forms sheets of great area. In spite of its rapid growth it is frequently overgrown bySpongilla carteri.
19.Trochospongilla phillottiana*,Annandale.
Trochospongilla phillottiana, Annandale, J. Asiat. Soc. Bengal, 1907, p. 22, fig. 6.Trochospongilla phillottiana,id., Rec. Ind. Mus. i, p. 269 (1907).Trochospongilla phillottiana,id.,ibid.ii, p. 157 (1908).
Spongehard but friable, forming sheets or patches often of great extent but never more than about 5 mm. thick; the surface minutely hispid, flat; colour pale yellow, the golden-yellow gemmules shining through the sponge in a very conspicuous manner; oscula inconspicuous; external membrane adherent; no basal chitinous membrane.
Skeletondense but by no means strong; the reticulation close but produced mainly by single spicules, which form triangular meshes; radiating fibres never very distinct, only persisting for a short distance in a vertical direction; each gemmule enclosed in an open, irregular cage of skeleton-spicules.
Spicules.Skeleton-spicules short, slender, blunt, more or less regularly and strongly spiny, straight or feebly curved. No flesh-spicules. Gemmule-spicules with the rotulæ circular, very wide as compared with the shaft, concave on the surface, with the shaft projecting as an umbo on the surface; the lower rotula often a littlelargerthan the upper.
Gemmulesnumerous, situated at the base of the sponge in irregular, one-layered patches, small (0.32 × 0.264 mm.), of a brilliant golden colour, distinctly wider than high, with a single aperture situated on an eminence on the apex, each clothed (when mature) with a pneumatic coat that contains relatively large but irregular air-spaces among which the spicules stand with the rotulæ overlapping alternately, a funnel-shaped pit in the coat descending from the surface to the upper rotula of each of them; the surface of the gemmule covered with irregular projections.
This species appears to be related toT. pennsylvanica, from which it differs mainly in the form of its gemmule-spicules and the structure of its gemmule. My original description was based on specimens in which the gemmule-spicules were not quite mature.
Typein the Indian Museum.
Geographical Distribution.—Lower Bengal and Lower Burma.Localities:—Bengal, Calcutta (Annandale):Burma, jungle pool near Kawkareik, Amherst district, Tenasserim (Annandale).
Biology.—This species covers a brick wall at the edge of the Museum tank in Calcutta every year during the "rains." In the cold weather the wall is left dry, but it is usually submerged to a depth of several feet before the middle of July. It is then rapidly covered by a thin layer of the sponge, which dies down as soon as the water begins to sink when the "rains" are over. For some months the gemmules adhere to the wall on account of the cage of spicules in which each of them is enclosed, but long before the water rises again the cages disintegrate and the gemmules are set free. Many of them fall or are carried by the wind into the water, on the surface of which, owing to their thick pneumatic coat, they float buoyantly. Others are lodged in cavities in the wall. On the water the force of gravity attracts them to one another and to the edge of the pond, and as the water rises they are carried against the wall and germinate. In thick jungle at the base of the Dawna Hills near Kawkareik[AI]in the interior of Tenasserim, I found the leaves of shrubs which grew round a small pool, covered with little dry patches of the sponge, which had evidently grown upon them when the bushes were submerged. This was in March, during an unusually severe drought.
20.Trochospongilla pennsylvanica* (Potts).
Tubella pennsylvanica, Potts, P. Ac. Philad. 1882, p. 14.Tubella pennsylvanica,id.,ibid.1887, p. 251, pl. vi, fig. 2, pl. xii, figs. 1-3.Tubella pennsylvanica, Mackay, Trans. Roy. Soc. Canada, 1889, Sec. iv, p. 95.Tubella pennsylvanica, Hanitsch, Nature, li, p. 511 (1895).Tubella pennsylvanica, Weltner, Arch. Naturg. lxi (i), p. 128 (1895).Tubella pennsylvanica, Hanitsch, Irish Natural. iv, p. 129 (1895).Tubella pennsylvanica, Annandale, J. Linn. Soc., Zool., xxx, p. 248 (1908).Tubella pennsylvanica,id., Rec. Ind. Mus. iii, p. 102 (1909).Tubellapennsylvanica,id., P. U.S. Mus. xxxvii, p. 403, fig. 2 (1909).
Spongesoft, fragile, forming small cushion-shaped masses, grey or green; oscula few in number, often raised on sloping eminences surrounded by radiating furrows below the external membrane; external membrane adhering to the parenchyma.
Skeletonclose, almost structureless. "Surface of mature specimens often found covered with parallel skeleton spicules, not yet arranged to form cell-like interspaces" (Potts).
Spicules.Skeleton-spicules slender, cylindrical, almost straight, sharp or blunt, minutely, uniformly or almost uniformly spined; spines sometimes absent at the tips. No flesh-spicules. Gemmule-spicules with the lower rotula invariably larger than the upper; both rotulæ flat or somewhat sinuous in profile, usually circular but sometimes asymmetrical or subquadrate in outline, varying considerably in size.
Gemmulessmall, numerous or altogether absent, covered with a granular pneumatic coat of variable thickness; the rotulæ of the gemmule-spicules overlapping and sometimes projecting out of the granular coat.
The measurements of the spicules and gemmules of an Indian specimen and of one from Lehigh Gap, Pennsylvania, are given for comparison:—
The spicules of the Travancore specimen are, therefore, a trifle larger than those of the American one, but the proportions are closely similar.
The difference between the gemmule-spicules of this species and those of such a form asT. phillottianais merely one of degree and can hardly be regarded as a sufficient justification for placing the two species in different genera. If, as I have proposed, we confine the generic nameTubellato those species in which the gemmule-spicules are really like "little trumpets," the arrangement is a much more natural one, for these species have much in common apart from the gemmule-spicules.T. pennsylvanicadoes not appear to be very closely related to any other known species exceptT. phillottiana.
Typein the U.S. National Museum, from which specimens that appear to be co-types have been sent to the Indian Museum.
Geographical Distribution.—Very wide and apparently discontinuous:—N. America (widely distributed), Ireland (Hanitsch), Hebrides of Scotland (Annandale), Travancore, S. India (Annandale). The only Indian locality whence I have obtained specimens is Shasthancottah Lake near Quilon in Travancore.
Biology.—In Shasthancottah LakeT. pennsylvanicais found on the roots of water-plants that are matted together to form floating islands. It appears to avoid light and can only be obtained from roots that have been pulled out from under the islands. In Scotland I found it on the lower surface of stones near the edge of Loch Baa, Isle of Mull. In such circumstances the sponge is of a greyish colour, but specimens of thevarietyminimataken by Potts on rocks and boulders in Bear Lake, Pennsylvania, were of a bright green.
Sponges taken in Travancore in November were full of gemmules; in my Scottish specimens (taken in October) I can find no traces of these bodies, but embryos are numerous.
Genus 6.TUBELLA,Carter.
Tubella, Carter, Ann. Nat. Hist. (5) vii, p. 96 (1881).Tubella, Potts (partim), P. Ac. Philad. 1887, p. 248.Tubella, Weltner (partim), Arch. Naturg. lxi (i), p. 128 (1895).
Type,Spongilla paulula, Bowerbank.
This genus is distinguished fromEphydatiaandTrochospongillaby the fact that the two ends of the gemmule-spicules are unlike not only in size but also in form. It sometimes happens that this unlikeness is not so marked in some spicules as in others, but in some if not in all the upper end of the shaft (that is to say the end furthest removed from the inner coat of the gemmule in the natural position) is reduced to a rounded knob, while the lower end expands into a flat transverse disk with a smooth or denticulated edge. The spicule thus resembles a little trumpet resting on its mouth. The shaft of the spicule is generally slender and of considerable length. The skeleton of the sponge is as a rule distinctly reticulate and often hard; the skeleton-spicules are either slender or stout and sometimes change considerably in proportions and outline as they approach the gemmules.
Geographical Distribution.—The genus is widely distributed in the tropics of both Hemispheres, its headquarters apparently being in S. America; but it is nowhere rich in species. Only two are known from the Oriental Region, namelyT. vesparium* from Borneo, andT. vesparioides* from Burma.
21.Tubella vesparioides*,Annandale. (Plate II, fig. 4.)
Tubella vesparioides, Annandale, Rec. Ind. Mus. ii, p. 157 (1908).
Spongeforming rather thick sheets of considerable size, hard but brittle, almost black in colour; oscula inconspicuous; external membrane supported on a reticulate horizontal skeleton.
Skeleton.The surface covered with a network of stout spicule-fibres, the interstices of which are more or less deeply sunk, with sharp fibres projecting vertically upwards at the nodes; the whole mass pervaded by a similar network, which is composed of a considerable number of spicules lying parallel to one another,overlapping at the ends and bound together by a profuse secretion of spongin.
Illustration: Fig. 25.—Spicules of Tubella vesparioides (from type specimen). × 240.Fig. 25.—Spicules ofTubella vesparioides(from type specimen). × 240.
Fig. 25.—Spicules ofTubella vesparioides(from type specimen). × 240.
Spicules.Skeleton-spicules slender, smooth, amphioxous, bent in a wide arc or, not infrequently, at an angle. No true flesh-spicules. Gemmule-spicules terminating above in a rounded, knob-like structure and below in a relatively broad, flat rotula, which is very deeply and irregularly indented round the edge when mature, the spicules at an earlier stage of development having the form of a sharp pin with a round head; shaft of adult spicules projecting slightly below the rotula, long, slender, generally armed with a few stout conical spines, which stand out at right angles to it.
Gemmulesnumerous throughout the sponge, spherical, provided with a short, straight foraminal tubule, surrounded by one row of spicules, which are embedded in a rather thin granular coat.
This sponge is closely related toTubella vesparium(v. Martens) from Borneo, from which it may be distinguished by its smooth skeleton-spicules and the deeply indented disk of its gemmule-spicules.The skeleton-fibres are also rather less stout. By the kindness of Dr. Weltner, I have been able to compare types of the two species.
Typein the Indian Museum.
Habitat.—Taken at the edge of the Kanghyi ("great pond") at Mudon near Moulmein in the Amherst district of Tenasserim. The specimens were obtained in March in a dry state and had grown on logs and branches which had evidently been submerged earlier in the year. The namevespariumgiven to the allied species on account of its resemblance to a wasps' nest applies with almost equal force to this Burmese form.
Genus 7.CORVOSPONGILLA, nov.
Type[AJ],Spongilla loricata, Weltner.
Spongillidæ in which the gemmule-spicules are without a trace of rotulæ and the flesh-spicules have slender cylindrical shafts that bear at or near either end a circle of strong recurved spines. The gemmule-spicules are usually stout and sausage-shaped, and the gemmules resemble those ofStratospongillain structure. The skeleton is strong and the skeleton-spicules stout, both resembling those of the "genus"Potamolepis, Marshall.
As in all other genera of Spongillidæ the structure of the skeleton is somewhat variable, the spicule-fibres of which it is composed being much more distinct in some species than in others. The skeleton-spicules are often very numerous and in some cases the skeleton is so compact and rigid that the sponge may be described as stony. The flesh-spicules closely resemble the gemmule-spicules of some species ofEphydatiaandHeteromeyenia.
Geographical Distribution.—The species of this genus are probably confined to Africa (whence at least four are known) and the Oriental Region. One has been recorded from Burma and another from the Bombay Presidency.
Key to the Indian Species ofCorvospongilla.
22.Corvospongilla burmanica* (Kirkpatrick). (Plate II, fig. 5.)
Spongilla loricatavar.burmanica, Kirkpatrick, Rec. Ind. Mus. ii, p. 97, pl. ix (1908).
Spongeforming a shallow sheet, hard, not very strong, of a pale brownish colour; the surface irregularly spiny; the oscula small but conspicuous, circular, raised on little turret-like eminences; the external membrane adhering closely to the sponge.
Skeletondense but by no means regular; the network composed largely of single spines; thick radiating fibres distinguishable in the upper part of the sponge.
Spicules.Skeleton-spicules smooth, not very stout, amphistrongylous, occasionally a little swollen at the ends, often with one or more fusiform swellings, measuring on an average about 0.27 × 0.0195 mm. Flesh-spicules with distinct rotules, the recurved spines numbering 4 to 6, measuring about 1/7 the length of the spicules; the shaft by no means strongly curved; their length from 0.03-0.045 mm. Gemmule-spicules amphioxous, as a rule distinctly curved, sometimes swollen at the ends, covered regularly but somewhat sparsely with fine spines, not measuring more than 0.49 × 0.078 mm.
Gemmulesstrongly adherent, arranged in small groups, either single or double; when single spherical, when double oval; each gemmule or pair of gemmules covered by two layers of gemmule-spicules bound together in chitinous substance; the inner layer on the inner coat of the gemmule, the outer one separated from it by a space and in contact with the outer cage of skeleton-spicules; the size of the gemmule-spicules variable in both layers; external to the outer layer a dense cage of skeleton-spicules; foraminal tubule short, cylindrical.
This sponge is closely related toS. loricata, Weltner, of which Kirkpatrick regards it as a variety. "The main difference," he writes, "between the typical African form and the Burmese variety consists in the former having much larger microstrongyles (83 × 15.7 µ [0.83 × 0.157 mm.]) with larger and coarser spines;... Judging from Prof. Weltner's sections of gemmules, these bodies lack the definite outer shell of smooth macrostrongyles [blunt skeleton-spicules], though this may not improbably be due to the breaking down and removal of this layer. A further difference consists in the presence, in the African specimen, of slender, finely spined strongyles [amphistrongyli], these being absent in the Burmese form, though perhaps this fact is not of much importance."
Typein the British Museum; a piece in the Indian Museum.
Habitat.—Myitkyo, head of the Pegu-Sittang canal, Lower Burma (E. W. Oates).
Biology.—The sponge had grown over a sheet of the polyzoonHislopia lacustris, Carter (see p. 204), remains of which can be detected on its lower surface.
"Mr. E. W. Oates, who collected and presented the sponge, writes that the specimen was found encrusting the vertical and horizontal surfaces of the bottom beam of a lock gate, where it covered an area of six square feet. The beam had been tarred several times before the sponge was discovered. The portion of the gate on which the sponge was growing was submerged from November to May for eight hours a day at spring tides, but was entirely dry during the six days of neap tides. From May to October it was constantly submerged. The sponge was found in April. Although the canal is subject to the tides, the water at the lock is always fresh. The colour of the sponge during life was the same as in its present condition."
23.Corvospongilla lapidosa* (Annandale).
Spongilla lapidosaAnnandale, Rec. Ind. Mus. ii, pp. 25, 26, figs. 3, 4, 5 (1908).
Thespongeforms a thin but extremely hard and resistant crust the surface of which is either level, slightly concave, or distinctly corrugated; occasional groups of spicules project from it, but their arrangement is neither so regular nor so close as is the case inC. burmanica. The dermal membrane adheres closely to the sponge. The oscula are small; some of them are raised above the general surface but not on regular turret-shaped eminences. The colour is grey or black. There is a thick chitinous membrane at the base of the sponge.
Illustration: Fig. 26.—Spicules of Corvospongilla lapidosa (from type specimen), × 240.Fig. 26.—Spicules ofCorvospongilla lapidosa(from type specimen), × 240.
Fig. 26.—Spicules ofCorvospongilla lapidosa(from type specimen), × 240.
Theskeletonis extremely dense owing to the large number of spicules it contains, but almost structureless; broad vertical groups of spicules occur but lack spongin and only traverse a small part of the thickness of the sponge; their position is irregular. The firmness of the skeleton is due almost entirely to the interlocking of individual spicules. At the base of the sponge the direction of a large proportion of the spicules is horizontal or nearly horizontal, the number arranged vertically being much greater in the upper part.
Spicules.The skeleton-spicules are sausage-shaped and often a little swollen at the ends or constricted in the middle. A large proportion are twisted or bent in various ways, and a few bear irregular projections or swellings. The majority, however, are quite smooth. Among them a few more or less slender, smooth amphioxi occur, but these are probably immature spicules. The length and curvature of the amphistrongyli varies considerably, but the averagemeasurementsare about 0.28 × 0.024 mm. The flesh-spicules also vary greatly in length and in the degree to which their shafts are curved. At first sight it seems to be possible to separate them into two categories, one in which the shaft is about 0.159 mm. long, and another in which it is only 0.05 mm. or even less; and groups of birotulates of approximately the same length often occur in the interstices of the skeleton. Spicules of all intermediate lengths can, however, be found. The average diameter of the shaft is 0.0026 mm. and of the rotula 0.0106 mm., and the rotula consists of from 6 to 8 spines. The gemmule-spicules vary greatly in size, the longest measuring about 0.08 × 0.014 and the smallest about 0.034 × 0.007 or even less. There appears to be in their case an even more distinct separation as regards size than there is in that of the flesh-spicules; but here again intermediate forms occur. They are all stout, more or less blunt, and more or less regularly covered with very short spines; most of them are distinctly curved, but some are quite straight.
Gemmules.The gemmules are firmly adherent to the support of the sponge, at the base of which they are congregated in groups of four or more. They vary considerably in size and shape, many of them being asymmetrical and some elongate and sausage-shaped. The latter consist of single gemmules and not of a pair in one case. Extreme forms measure 0.38 × 0.29 and 0.55 × 0.25. Each gemmule is covered with a thick chitinous membrane in close contact with its wall and surrounding it completely. This membrane is full of spicules arranged as in a mosaic; most or all of them belong to the smaller type, and as a rule they are fairly uniform in size. Separated from this layer by a considerable interval is another layer of spicules embedded in a chitinous membrane which is in continuity with the basal membrane of the sponge. The spicules in this membrane mostly belong to the larger type and are very variable in size; mingled with them are often a certain number of birotulate flesh-spicules. The membrane is in close contact with a dense cage of skeleton-spicules arranged parallel to it and bound together by chitinous substance. The walls of this cage, when they are in contact with those of the cages of other gemmules, are coterminous with them. There is a single depressed aperture in the gemmules, as a rule situated on one of the longer sides.
This sponge is distinguished fromC. burmanicanot only by differences in external form, in the proportions of the spicules and the structure of the skeleton, but also by the peculiar nature of the armature of the gemmule. The fact that birotulate spiculesare often found in close association with them, is particularly noteworthy.
Typein the Indian Museum.
Geographical Distribution.—This sponge has only been found in the Western Ghats of the Bombay Presidency.Localities:—Igatpuri Lake and the R. Godaveri at Nasik.
Biology.—There is a remarkable difference in external form between the specimens taken in Igatpuri and those from Nasik, and this difference is apparently due directly to environment. In the lake, the waters of which are free from mud, the sponges were growing on the lower surface of stones near the edge. They formed small crusts not more than about 5 cm. (2 inches) in diameter and of a pale greyish colour. Their surface was flat or undulated gently, except round the oscula where it was raised into sharply conical eminences with furrowed sides. The specimens from Nasik, which is about 30 miles from Igatpuri, were attached, together with specimens ofSpongilla cinereaandS. indica, to the sides of a stone conduit full of very muddy running water. They were black in colour, formed broad sheets and were markedly corrugated on the surface. Their oscula were not raised on conical eminences and were altogether most inconspicuous. The skeleton was also harder than that of sponges from the lake.
In the lakeC. lapidosawas accompanied by the gemmules ofSpongilla bombayensis, but it is interesting that whereas the latter sponge was entirely in a resting condition, the former was in full vegetative vigour, a fact which proves, if proof were necessary, that the similar conditions of environment do not invariably have the same effect on different species of Spongillidæ.
[W]O. von Linstow, Rec. Ind. Mus. i, p. 45 (1907).
[X]W. M. Tattersall,ibid., ii, p. 236 (1908).
[Y]T. R. R. Stebbing,ibid., i, p. 160 (1907); and N. Annandale,ibid., ii, p. 107 (1908).
[Z]Mr. Stebbing has been kind enough to examine specimens of this isopod, which he will shortly describe in the Records of the Indian Museum.S. walkeri, its nearest ally, was originally described from the Gulf of Manaar, where it was taken in a tow-net gathering (see Stebbing in Herdman's Report on the Ceylon Pearl Fisheries, pt. iv, p. 31 (1905)).
[AA]See M. and A. Weber in M. Weber's Zool. Ergeb. Niederl. Ost-Ind. vol. i, p. 48, pl. v (1890).
[AB]Mr. C. A. Paiva, Assistant in the Indian Museum, has lately (March 31st, 1911) obtained specimens ofS. crateriformisin a small pond of fresh water on Ross Island in the Andaman group. The existence of this widely distributed species on an oceanic island is noteworthy.
[AC]The only complete European specimen of the species I have seen differs considerably in outward form from any Indian variety, consisting of a flat basal area from which short, cylindrical turret-like branches arise. This specimen is from Lake Balaton in Hungary and was sent me by Prof. von Daday de Dees of Buda-Pesth.
[AD]Needham. Rec. Ind. Mus. iii, p. 206 (1909).
[AE]According to the late Rai Bahadur R. B. Sanyal, freshwater sponges are called in Bengali "shrimps' nests." From his description it is evident that he refers mainly toS. carteri(see Hours with Nature, p. 46; Calcutta 1896).
[AF]Stebbing, J. Linn. Soc. xxx, p. 40; Annandale, Rec. Ind. Mus. i, p. 279.
[AG]Brunetti, Rec. Ind. Mus. ii, p. 376 (1908).
[AH]The outer covering by means of which the gemmule is fixed is not formed until the other structures are complete. In young sponges, therefore, free gemmules may often be found.
[AI]This locality is often referred to in zoological literature as Kawkareetor Kawkarit, or even Kokarit.
[AJ]Potts'sSpongilla novæ-terræfrom Newfoundland and N. America cannot belong to this genus although it has similar flesh-spicules, for, as Weltner has pointed out (op. cit. suprap. 126), the gemmule-spicules are abortive rotulæ. This is shown very clearly in the figure published by Petr (Rozp. Ceske Ak. Praze,Trída, ii, pl. ii, figs. 27, 28, 1899), who assigns the species toHeteromeyenia. Weltner places it inEphydatia, and it seems to be a connecting link between the two genera. It has been suggested that it is a hybrid (Traxler, Termes. Fuzetek, xxi, p. 314, 1898).
APPENDIX TO PART I.
Form of Uncertain Position.
(Plate I, fig. 4.)
On more than one occasion I have found in my aquarium in Calcutta small sponges of a peculiar type which I am unable to refer with certainty to any of the species described above. Fig. 4, pl. I, represents one of these sponges. They are never more than about a quarter of an inch in diameter and never possess more than one osculum. They are cushion-shaped, colourless and soft. The skeleton-spicules are smooth, sharply pointed, moderately slender and relatively large. They are arranged in definite vertical groups, which project through the dermal membrane, and in irregular transverse formation. Small spherical gemmules are present but have only a thin chitinous covering without spicules or foramen.
These sponges probably represent an abnormal form of some well-known species, possibly ofSpongilla carteri. I have seen nothing like them in natural conditions.
I.
The Phylum Cœlenterata and the Class Hydrozoa.
The second of the great groups or phyla into which the metazoa are divided is the Cœlenterata, in which are included most of the animals commonly known as zoophytes, and also the corals, sea-anemones and jelly-fish. These animals are distinguished from the sponges on the one hand and from the worms, molluscs, arthropods, vertebrates, etc., on the other by possessing a central cavity (the cœlenteron or "hollow inside") the walls of which are the walls of the body and consist oftwolayers of cells separated by a structureless, or apparently structureless, jelly. This cavity has as a main function that of a digestive cavity.
An ideally simple cœlenterate would not differ much in general appearance from an olynthus (p. 27), but it would have no pores in the body-wall and its upper orifice would probably be surrounded by prolongations of the body-wall in the form of tentacles. There would be no collar-cells, and the cells of the body generally would have a much more fixed and definite position and more regular functions than those of any sponge. The most characteristic of them would be the so-called cnidoblasts. Each of these cells contains a capsule[AK]from which a long thread-like body can be suddenly uncoiled and shot out.
The simplest in structure of the cœlenterates are those that constitute the class Hydrozoa. In this class the primitive central cavity is not divided up by muscular partitions and there is no folding in of the anterior part of the body to form an œsophagus or stomatodæum such as is found in the sea-anemones and coralpolyps. In many species and genera the life-history is complex, illustrating what is called the alternation of generations. That is to say, only alternate generations attain sexual maturity, those that do so being produced as buds from a sexless generation, which itself arises from the fertilized eggs of a previous sexual generation. The sexual forms as a rule differ considerably in structure from the sexless ones; many medusæ are the sexual individuals in a life-cycle in which those of the sexless generation are sedentary.
An excellent general account of the cœlenterates will be found in the Cambridge Natural History, vol. i (by Prof. Hickson).
STRUCTURE OF HYDRA.
Hydra, the freshwater polyp, is one of the simplest of the Hydrozoa both as regards structure and as regards life-history. Indeed, it differs little as regards structure from the ideally simple cœlenterate sketched in a former paragraph, while its descent is direct from one polyp to another, every generation laying its own eggs[AL]. The animal may be described as consisting of the following parts:—(1) an upright (or potentially upright) column or body, (2) a circle of contractile tentacles at the upper extremity of the column, (3) an oral disk or peristome surrounding the mouth and surrounded by the tentacles, and (4) a basal or aboral disk at the opposite extremity. The whole animal is soft and naked. The column, when the animal is at rest, is almost cylindrical in some forms but in others has the basal part distinctly narrower than the upper part. It is highly contractile and when contracted sometimes assumes an annulate appearance; but as a rule the external surface is smooth.
The tentacles vary in number, but are never very numerous. They are disposed in a single circle round the oral disk and are hollow, each containing a prolongation of the central cavity of the column. Like the column but to an even greater degree they are contractile, and in some forms they are capable of great elongation. They cannot seize any object between them, but are able to move in all directions.
The disk that surrounds the mouth, which is a circular aperture, is narrow and can to some extent assume the form of a conical proboscis, although this feature is never so marked as it is in some hydroids. The basal disk is even narrower and is not splayed out round the edges.