12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 95 



Silvanidae (pi. 3, G). 



The customary division of the labium into a first prementum 

 {IPrmt), a second prementum (IlPrmt) and a postmentum {Pint) 

 is found in Orysaephitus. The first prementum carries the palpi and 

 one pair of setae. The second prementum also bears a pair of setae 

 situated just before the middle. The postmentum is shorter than the 

 second prementum and at its posterolateral margins are located the 

 posterior tentorial pits {pt). On the postmentum also are found two 

 setae, near its anterior boundary. 



The ventral muscles consist of two pairs, the ventral adductors of 

 the labium (2adlb) and the retractors of the prementum (rst). The 

 latter have their origin on the postmentum in the region of the ten- 

 torial pits and insert on the base of the second prementum. The ad- 

 ductor muscles also arise from the inner surface of the postmental 

 sclerite, medial to the retractor muscles. They insert on the base of 

 the first prementum. 



Cucujidae (pi. 3, F). 



The labium of Cucujus shows the usual three subdivisions. The 

 distal part, which bears the palpi and is separated from the proximal 

 parts by a distinct membranous area, is the first prementum (IPrmt). 

 The second prementum (IlPrmt) is separated from the postmentum 

 by a second membranous area. The postmentum (Pmt) and the gula 

 (Gu) are fused into one sclerite with no dividing suture. This sclero- 

 tized area is bounded laterally by the posterior tentorial pits (pt) and 

 the postoccipital suture (pos), and posteriorly by the margin of the 

 foramen. The gula is interpreted as that portion of this sclerite 

 which lies posterior to an imaginary line connecting the posterior 

 tentorial pits. 



The ventral adductors of the labium (2adlb), as in Byrrhus, arise 

 from the postmentum instead of from the tentorium. These points 

 of origin, however, are on a line with the posterior tentorial pits, and 

 it is apparent that they have migrated from the tentorial bridge to 

 their present location. Their points of insertion, on the base of the 

 first prementum, are consistent. The retractors of the prementum 

 {rst) arise from the customary place on the postmentum, slightly 

 anterior to a line connecting the tentorial pits. 



Laemophloeidae (pi. 3, H). 



In Eunausihius the labium is separated into three regions, the first 

 and second subdivisions of the prementum, and the postmentum. The 

 first prementum (IPrmt) bears the palpi. The second prementum 

 (IlPrmt) is marked ofif anteriorly and posteriorly by distinct sutures. 

 The latter area bears a pair of setae which are situated slightly before 



