238 ANATOMY. 



Coleoptera, although some portions of the thorax, namely, the pro- 

 thorax, do not form so complex a frame as in Gryllotalpa. 



The prothorax consists in the majority of beetles of two separated 

 pieces, which, only in some capricorns (Cattichroma, Saperda,) and all 

 the Rhynchophora, are connate *. In Carabux, Dyticus, Bupreslis 

 there lies between both two other free pieces, which I have called omia, 

 and which must be considered as the free lateral walls of the dorsal 

 plate. The moveable spines in Acrocinus longimanus (Kirby and 

 Spence's Umbones) are probably these same pieces, at least we can 

 give no other explanation of these otherwise perplexing organs. The 

 internal skeleton of the prothorax consists in a process originating 

 from the prosternum between the cavities of the coxae, which divides 

 itself into two when those cavities are distant from each other (Qryctes). 

 Above, this process has a tooth on each side, which bends towards the 

 side of the prothorax, and sometimes unites with it (in Hydrophilus, 

 PI. X. No. 3. f. t> and 7- a, a). It has frequently more or less the 

 appearance of a fork, or the letter Y, and Kirby and Spence thence 

 call it antefurca, a name which, notwithstanding its bad construction, 

 does not suit, because this process does not always furcate, and is 

 indeed wanting in many beetles, namely, in those with a simple 

 prothorax. In such cases a partition between the cavities of the coxae 

 occupies its place. I call it, when present and of importance, the 

 processus interims prosterni. The nervous cord passes between its 

 branches. 



In the mesothorax the partition or prophragma descends from the 

 anterior margin of the mesonotum, and is directed somewhat forward. 

 It is in general but very short, and rather a small ridge, to which the 

 connecting muscles of the meso- and metathorax are attached. We 

 again find the internal process upon the mesosternum, but here it ori- 

 ginates with more widely divided shanks, each of which shanks forms 

 an arch, which, as in Cicada, spans the aperture of the cavities of the 

 coxae, and ascends as high as the suture of the scapulae, to unite itself 

 with the surrounding margin of that part. In the Lamellicornia this 

 arch does not reach the suture, but projects freely into the cavity, serv- 

 ing as a point of attachment for the muscles. In this shape the entire 



* Meckel erroneously says this of all. See his Vergleich. Anatomic, vol. ii. Part i. 

 ?. 70. 



