l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



a dorsal arm (dta). The posterior arm extends along the ventral wall 

 of the head to the foramen magnum, with the edge of which it is com- 

 pletely united. It is marked on the exterior of the head by a small 

 pit or invagination at the cephalic end of the gular sutures. This is 

 the posterior tentorial pit (ptp). The anterior arm of the tentorium 

 extends to the anterior dorsal region of the head near the base of the 

 antennae. The point at which it reaches the head wall is marked on 

 the exterior by a shallow anterior tentorial pit (atp). This is situated 

 just mesad of the antennal fossa (o/) . The dorsal arm of the tentorium 

 extends dorsad and somewhat caudad to the dorsal wall of the head. 

 This point is marked on the exterior by a slight unevenness of the 

 surface, and the body wall itself is much thinner, or at least less 

 heavily pigmented, at that place. This point (dtp) represents the 

 dorsal tentorial pit. The two halves of the tentorium meet and fuse 

 at the midline of the head just caudad of the line of the base of the 

 mandibles. This union is the cephalic bridge or body of the tentorium 

 (cp). There has apparently been no study of the muscles which are 

 attached to the tentoria of Coleoptera, but the normal insect type is 

 given by Snodgrass (1928), who shows that many of the muscles of 

 the mouthparts and antennae are attached to specific parts of the 

 tentorium. 



THE CERVIX 



The neck region or cervix is largely membranous but contains cer- 

 tain sclerites which have been interpreted by some writers as parts 

 of a primitive cervical segment. Three pairs of sclerites are present 

 in this species. Two of these pairs lie in the membrane at the lateral 

 lx)sterior corners of the gula. The third pair is more closely united 

 to the prothorax, and in dissections is most frequently retained on the 

 lateral cephalic edges of the prosternum. 



In the dorsal parts of the membrane near its union with the thorax 

 are two areas bearing a few short setae. They are not sharply defined 

 and are apparently unsclerotized. 



THE THORAX 



The thorax is very obviously divided into two regions, owing to the 

 distinct separation of the prothorax from the rest (fig. 3 A) and the 

 close union of the mesothorax and metathorax to the abdomen. 



The pronotum (fig. 3 A. pron) occupies the entire dorsal aspect 

 of the prothorax. Its posterior and lateral margins are inflexed upon 

 the ventral surface and are separated from the sternum by the sterno- 



