of Buprestidse and Elateridse. 187 



as a separate piece a small part of the skeleton situated near the 

 root of the coxae and called by him the trochantin, only very 

 little attention was paid to it. The modern examinations of the 

 external skeleton of insects, undertaken for the purpose of dis- 

 covering useful marks of distinction for the numberless genera 

 and other divisions established by entomologists according to a 

 general impression of the habitus of the animals, have, however, 

 in some cases led to the tiochantins being taken into considera- 

 tion ; and they are said to exist in some cases, but to be wanting 

 in others. This view, however, appears to be erroneous. They 

 seem never to be wanting in Coleopteia (to which we are now 

 particularly alluding), although they vary very much in size and 

 shape; and the difference in question would be more correctly 

 indicated by describing the trochautins as either covered by a 

 prolongation of those plates of the skeleton which surround 

 the coxae, or uncovered and bare. At the same time, however, 

 cases would occur in which it might be difficult to say whether 

 the trochautins should be called covered or uncovered, as in 

 some instances they are not visible till the coxsc are turned back 

 in their sockets. Besides this, the definition of the family of 

 Bu))restid?e now generally adopted contains another still more 

 misli'ading feature — that part of their thorax which has been 

 called the trochantin being an entirely different pii^ce and having 

 nothing to do with the coxa. In one instance the common 

 interpretation has been exchanged for a new one ; but this new 

 interpretation is not only erroneous in itself, but does not agree 

 with a thorough understanding of the true structure of the pro- 

 thorax in insects. 



In Buprestidse, as well as in Elateridse, each of the anterior 

 coxae is on the outside surrounded partly by a receding pro- 

 longation of the prosternum, and partly by a portion of the lower 

 edge of the epimeron. In the first group of the family of Ela- 

 teridae (see my classification below) these lateral laps of the pro- 

 sternum are very short; but in the second group of Elateridaeandin 

 Buprestidse they are so long that they occupy about the same space 

 as the epimera on the outer margin of the coxa. In all Elateridae 

 the laps of the prosternum and the epimera join so closely that the 

 upper and outer j)art of the coxa, and with it the trochantin, are 

 entirely hidden ; whilst in Buprestidae the parts in question do not 

 join closely, whereby the socket of the coxa receives a small and 

 narrow extension on the outside, and in this open groove a part 

 of the coxa is always seen, whilst the little round trochantin 

 itself is not seen, unless the coxa is turned back a little. It is 

 therefore better to express the difference between these two 

 families in this respect by drawing attention to the opening be- 

 tween the prosternum and epimera than by saying that the 



