Note 7 — LETTER XXVIII.

The insection that distinguishes these parts, the abdomen especially, is most visible in the majority of the Hymenoptera and Diptera orders; next in some Coleoptera, as the Lamellicorn tribes, &c. and the Lepidoptera. Latreille is of opinion, that the two last segments of the thorax in some insects are represented by the first of the abdomen, and that the upper half segment of this part in Coleoptera also represents the same. Latr. De quelques Appendices, &c. Annales Générales des Sciences Physiques. A Bruxelles, vi. livrais, xviii. 14. In fact, in the Lepidoptera, when the abdomen is separated from the trunk, this segment usually remains attached to the latter. In the Myriapods, the trunk is to be distinguished from the abdomen only by its bearing the three first pair of legs.