COLEOPTERA. 37 



but the hind pair are covered by the wing-cases, the extremity of the 

 thigh only appearing beyond the sides of the body. In some i'vw 

 species of Brachelytra, as already mentioned, the limbs are so firmly 

 soldered to the body, and apparently under a single sheath, that the 

 pupa might almost be termed an obtected one. Some pupa; are 

 enclosed in the cases in M'hich the larvai resided; but the habitations, 

 economy, habits, and period of duration in the various states of these 

 insects vary exceedingly. 



Naturalists are indebted to Aristotle for the establishment of this 

 order of insects, which embraced, according to his definition, all insects 

 with encased wings, " oa-cc to Tvrepov ex^i. bv KoXeai," and which has been 

 adopted by subsequent authors. Fabricius, howevei-, changed its 

 name to Eleutherata, and Clairvillc to Elytroptera. 



Linnasus described 891 species of these insects, which he divided 

 into 29 genera, distributed into the three following sections : — 

 *Antennis clavatis extrorsum incrassatis, * * Antennis filifor- 

 mibus, and * * * Antennis setaceis. GeofFroy proposed numerous 

 additional generic groups, and adopted a different mode of classifi- 

 cation, dividing the order into two primary sections, from the elytra 

 entirely or partially covering the abdomen, and subdividing these 

 sections according to the numerical variations in the joints of the tarsi. 

 This latter character was subsequently adopted by Olivier to distin- 

 guish the primary sections of the order, which were thence named 

 as follows : — \, Pentamera, in \\h\ch. all the tarsi are 5-jointed; 2. 

 ffeteromera, in which the four anterior tarsi are 5-jointed and the 

 two posterior 4-jointed ; 3. Tetramerd, which have four joints in all 

 the tarsi ; and 4. Trimera, having only three joints in all the tarsi. To 

 the four above-mentioned groups Latreille added another, named 

 Dim era, comjiosed of the minute family Pselaphida;, which were 

 supposed to have only two joints in all their tarsi. He, also in the 

 Reg)ie anirnaL proposed a sixth section, Monomera, for the rece])tion 

 of the Clambus armadillo, supposed to possess but a single joint in the 

 tarsi ; but the real affinities of these insects (the former with the 

 Staphylinidte,' and the latter with the Agathidiida;), as well as tlie 

 real structure of the tarsi, do not warrant the establishment of these 

 two sections, the Pselaphidae having three joints, and the Clambus, as I 

 have ascertained, having four joints at the least in the tarsi. Cuvier, 

 in his Tableau JEleme?itaire,di\'ided the order into 13 principal divisions, 

 characterised by the forms of the antenna;, tarsi, palpi, and elytra. 

 A . D 3 . __ 



