AMERICAN COLEOPTERA. 309 



part of the coxa and dilated only at the articuhition somewhat after 

 the manner of certain Elateridae. In two of the genera the elytra 

 are not margined and there is no separation of any epipleural portion. 

 Erapelus however reverts to the general type with distinct margin 

 and epipleurae. 



In Clambus and Calyptomerus the middle coxae are very narrowly 

 separated by a thin lamina while in Empelus the separation is well 

 marked. In the first two the mesosternum is almost hidden and the 

 metasternum is concave in front, the depression limited behind by a 

 well marked arcuate edge. In Empelus however there is no such 

 structure, the mesosternum is quite distinct and the metasternum not 

 concave. This excavation of the metasternum has already been fore- 

 shadowed in certain Agathidium {oniscoides, etc.), and has already 

 been described and its meaning indicated. 



One of the most curious characters in the tribe is found in the 

 method of insertion of the antennae. In Empelus the sides of the 

 front, a little distance in advance of the eyes, are simply sinuate, the 

 basal joint is here inserted and the antennae in repose pass under the 

 head to a distinct groove. In Clambus there is apparently a triangular 

 notch, but on closer examination it will be observed that the sides of 

 the head are acutely margined and that portion of the acute margin 

 appears to pass under the head and become continuous with the ridge 

 which defines the inner edge of the anteunal groove. The antennae 

 arise close to the eyes in Clambus. In Calyptomerus however the 

 structure is quite distinct. The antennae arise at a distance in front 

 of the eye midway between it and the middle of the front, the sides 

 of the head are acute as in Clambus, an edge or margin passing 

 forward from. the front of the eye while the frontal margin passes 

 backward and dips under the other, continuing in a ridge beneath 

 the head as in Clambus. Between the two ridges thus formed the 

 antennae arise and the first joint is concealed and may readily escape 

 detection. 



The manner in which the antennae are disposed of beneath the 

 head requires special mention. Attention has already been directed 

 to the ridge which is the inner limit of the antennal grooves or 

 cavities beneath the head. In Empelus and Clambus this ridge is 

 nearly straight and not very distant from the inner edge of the eye. 

 In the former genus the stem of the antenna lies close against this 

 ridge when in repose, the clavicular portion being then bent and 

 resting in an arcuate groove which crosses the gula from one side 



