188 Prof. J. C. Schiddte on the Classification 
trochantin is visible in Buprestidee, hidden in Elateride. But if 
we say, as authors usually have said hitherto*, that only Bupres- 
tidee possess trochantins, which are wanting in Elateridze, then the 
real fact is entirely missed. And if other authors, as Lacordaire 
and Thomson, go further, and state that the trochantins are 
very large and prominent in Buprestide, 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 explicable; for the laps in question are in 
Buprestide separated from the rest of the prosternum by a more 
or less deep groove, whereby they assume the appearance of being 
connected with the cox. 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 
(pleuree) 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 strictiori; nor do we ever find such a division carried out, 
* Lacordaire, Gen. des Coléop. iv. 1. pp. 90, 94, 130; Leconte, Classif. of 
the Coleopt. of N. Amer. i. pp. 156, 158, 159; Thomson, Skandinay. Coleopt. 
vi. pp. 6, 56. 
