Having given you these tables of theOrders, from a comparison of which you will be able to trace the improvements in his system made by this learned Entomologist in the interval of eight years, I shall proceed to give those of his subordinate groups arranged under each. This I have already done, to save space, in theArachnidaandInsecta aptera.
If you examine theOrdersas here given, you will find that they mostly representnatural primarygroups of his Classes, though with regard to theirdistributionyou may perhaps feel disposed to differ from him. You will also think that hissecondaryandminorgroups[1433], with the exception of some of his sections, merit the same character. Indeed, he has left far behind all his predecessorsin the progress that he has made towards extricating the true system. Setting out from a common centre he holds on his unwearied course, endeavouring to trace every set of objects that branches from it to its extreme term. But though he studied insectsanalyticallywith unrivalled success, he was not always equally happy in hissyntheticalarrangement of them. I do not here so much speak of the result which must necessarily follow from any arrangement in aseries, and which cannot well be avoided; but I allude particularly to his intire adoption of the Geoffroyan system in theColeoptera, which has prevented him in many instances from seeing the natural distribution of his groups.
In 1798, two years after the publication of Latreille's first enunciation of his system, M. Clairville, a very acute and learned Swiss Entomologist, drew up the following analytical table of insects.
Every one will think that the change of the received names of the Orders, here denominated Sections, is perfectly needless. The principal merit of this system is the division of insects, tacitly pointed out by Fabricius, intotwo groups or subclasses, from the mode in which they take their food.
Lamarck,—whose merits as a Zoologist, except in one point[1434], are of the highest order,—in hisSystème des Animaux sans Vertèbres, which was published in 1801, adopts the above division of insects; but, after Aristotle[1435], he makes theHymenopteraan intermediate Order between the masticators and those that take their food by suction; he places theLepidopteraat the head of the latter, and theAphaniptera, which he denominatesAptera, at the end[1436]: the Hexapod, Octopod, and PolypodApterahe considers asArachnida[1437]. In his last great work (Histoire Naturelle des Animaux sans Vertèbres) he includes theHymenopteraamongst the masticators, and reverses the disposition of his Orders, beginning with hisApteraand ending with theColeoptera[1438].
M. Le Baron Cuvier, in hisAnatomie Comparée(1805) dividedInsectainto two subclasses, from the presence or absence ofmaxillæ: thus—
HisGnathapterainclude the IsopodCrustacea, theArachnida, the Polypod, and some of the Octopod and HexapodAptera; and hisAptera—Pulex,Pediculus, andtheAcarina, with the exclusion ofHydrachna[1439]. It is remarkable enough that his Class as it stands, with a slight alteration, returns into itself, thus forming a circle; for his first Order (Gnathaptera) containsHydrachnaand theThysanura, and his last (Aptera) ends with theAnoplura, andAcarina.
All the French Entomologists have followed Olivier and Latreille in adopting, with some variation, Geoffroy's system with regard to theColeoptera, which has rendered them all more or less artificial. Dumeril has constructed a table of the Order, arranged differently from that above given[1440]of Latreille; but not more natural, for the very same reason.
Our learned countryman, Dr. Leach, by his zoological labours has thrown much light on the natural distribution of the Animal Kingdom, and no department of that kingdom is more indebted to him than theAnnulosa; of which I have before stated to you hisClasses[1441]. I shall now give a table of hisOrdersofArachnidaandInsectaLatr. and also his families, &c. of his ClassesMyriapodaandArachnides[1442].