]88 Prof. J. C, Schiodte on the Classification 



trochantin is visible in Buprestidse, hidden in Elateridse. But if 

 we say, as authors usually have said hitherto*, that only Bupres- 

 tidse possess trochantins, which are wanting in Elateridse, then the 

 real fact is entirely missed. And if other authors, as Lacordaire 

 and Thomson, go fui'ther, and state that the trochantins are 

 very large and prominent in Buprestidse, and put this forward 

 as one of their principal characters, then they must have over- 

 looked the real trochantins, which are very far from being large 

 or prominent, whilst the lateral prolongations of the proster- 

 num just mentioned have been mistaken for trochantins. Nor 

 is this mistake inexplicable; for the laps in question are in 

 Buprestidse separated from the rest of the prosternum by a more 

 or less deep groove, whereby they assume the appearance of being 

 connected with the coxae. But any such belief is at once dis- 

 pelled by turning the coxa about, in fresh or softened specimens, 

 when it will be seen that the supposed trochantin remains quietly 

 in its place, instead of following the movements of the coxa as 

 a real trochantin would ; and if the coxa is turned back in the 

 socket, the real trochantin will appear in the open groove. To 

 render the experiment still more convincing, detach the coxa 

 from its socket, and the true trochantin will be found sitting in 

 in its proper place, whilst the supposed trochantin shows itself 

 to form one piece with the prosternum. 



The only author who has refused to regard the lateral pro- 

 longations of the prosternum as trochantins is Von Kiesenwetter, 

 who, without further explanation, describes them as episterna 

 (Naturg. d. Insekten Deutsch. iv. p. 6). But, as already stated, 

 this seems to imply another mistake. What we call epimera in the 

 skeleton of Arthropoda are nothing but the chitinized side-folds 

 (pleurae) between the ventral and dorsal shields of the segments — 

 that is to say, (in the thorax of insects) between the pro-, meso-, 

 and metanotum above, and the pro-, meso-, and metasternum 

 beneath. In many insects having the thorax strongly chitinized 

 the epimera are found to be divided into two parts, of which the 

 foremost is called the episternum, whilst the hindmost is then 

 alone called the epimeron ; but this division is owing merely to 

 the necessity of procuring access for the air to the spiracles, 

 which open behind the epimera. As, however, the articulation 

 between the prothorax and mesothorax is so loose that the air 

 can always easily penetrate into the spiracula prothoracica 

 which are situated between them, there is no necessity for a 

 division of the epimera prothoracica into episterna and epimera 

 sensu stridiori', nor do we ever find such a division carried out, 



* Lacordaire, Gen. des Coleop. iv. 1. pp. 90, 94, 130 ; Leconte, Classif. of 

 the Coleopt. of N. Amer. i. pp. 166, 158, 159; Thomson, Skandinav. Coleopt. 

 vi. pp. 6, 56. 



