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As the majority of-authors consider this insect most nearly 
allied to the Longicorn family, it will he well first to compare 
it with these members to which it has most apparent kinship, 
and there is a great consensus of opinion that this is found 
in the genera Cyrtognathus (Fald) and Dorysthenes (Vigors). 
In these two genera, as in Hypocephalus — 
((x) The Mandibles are vertical — the palpi similar. 
(h) The head presents a similar peculiarity. Viz The 
contractile power of doubling itself U2^ under the pirothoraxy 
though the Cyrtognathus and Dorysthenes do not possess 
it in so marked a degree. The name Hypocephalus was 
suggested owing to this circumstance ; and nearly all speci- 
mens that have been discovered (the insect has never, I 
believe, been taken alive,) are thus contracted. 
(c) The presence of a membranous space on the under- 
side of the head — a space which Dr. Sharp and M. deLameere 
have discussed exhaustively ; the latter having discovered a 
double membrane, and in some instances certain lesions 
(blessures) or rents in this membrane, concerning the causes 
of which he can only hazard an explanation. In short, the 
configuration of tlie head, palpi, and mandibles, more nearly 
resemble Cyrtognathus than any other known Coleopteron. 
(d) The Elytra, again, are almost exactly similar to a rare 
Beetle, here exhibited from Ecuador, belonging to a nearly 
allied member of the Prionidse, the Prionacalus Buckleyi. 
Both are shagreened and a.re small in proportion to the 
size of the insect. 
But, per contra, the Antennce are unusually short. Spon- 
dylis buprestoides, however, an undoubted Longicorn, a 
native of Europe, has them no longer. 
The enormously protuberant Femora and legs, more 
resembling a Sagra, among the Phytophaga, than any Longi- 
corn — the large oval Prothorax — these are all foreign to the 
Cerambycidse. 
