Having given you these tables of the Orders, 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 the Arachnida and Insecta aptera.

If you examine the Orders as here given, you will find that they mostly represent natural primary groups of his Classes, though with regard to their distribution you may perhaps feel disposed to differ from him. You will also think that his secondary and minor groups[1433], with the exception of some of his sections, merit the same character. Indeed, he has left far behind all his predecessors in 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 insects analytically with unrivalled success, he was not always equally happy in his synthetical arrangement of them. I do not here so much speak of the result which must necessarily follow from any arrangement in a series, and which cannot well be avoided; but I allude particularly to his intire adoption of the Geoffroyan system in the Coleoptera, 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, into two 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 his Système des Animaux sans Vertèbres, which was published in 1801, adopts the above division of insects; but, after Aristotle[1435], he makes the Hymenoptera an intermediate Order between the masticators and those that take their food by suction; he places the Lepidoptera at the head of the latter, and the Aphaniptera, which he denominates Aptera, at the end[1436]: the Hexapod, Octopod, and Polypod Aptera he considers as Arachnida[1437]. In his last great work (Histoire Naturelle des Animaux sans Vertèbres) he includes the Hymenoptera amongst the masticators, and reverses the disposition of his Orders, beginning with his Aptera and ending with the Coleoptera[1438].

M. Le Baron Cuvier, in his Anatomie Comparée (1805) divided Insecta into two subclasses, from the presence or absence of maxillæ: thus—

His Gnathaptera include the Isopod Crustacea, the Arachnida, the Polypod, and some of the Octopod and Hexapod Aptera; and his Aptera—Pulex, Pediculus, and the Acarina, with the exclusion of Hydrachna[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) contains Hydrachna and the Thysanura, and his last (Aptera) ends with the Anoplura, and Acarina.

All the French Entomologists have followed Olivier and Latreille in adopting, with some variation, Geoffroy's system with regard to the Coleoptera, 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 the Annulosa; of which I have before stated to you his Classes[1441]. I shall now give a table of his Orders of Arachnida and Insecta Latr. and also his families, &c. of his Classes Myriapoda and Arachnides[1442].