118 THE ORDER OP COLEOPTERA. 



America: Stylo2)8,K.\rbj, with the antennae six-jointed; and Xetios, Eossi, 

 having the auteunne four-jointed. For a detailed description of these 

 insects the reader is referred to Westwood's Introduction, Vol. ii, page 

 287 ; or to Packard's Guide, page 481. 



Tribe Xm. 



HETEROMEROUS BARK-BEETLES. 



Reteromera corticicola. Stenelytra partly^ Latreille. 



This tribe includes all the Stenelytra of Latreille except the family of 

 Helopida3, which are now united to the Ground-beetles. The word Sien- 

 elytra means having narroiv wing-covers, and was given to these insects 

 on account of their more or less elongated and narrow forms. They are 

 distinguished from the i)arasitic beetles by the absence of a visible neck 

 and by the head being narrower than the thorax; and from the two 

 following tribes by the usually longer and more slender antennjc, by 

 the anterior coxic nearly or quite touching each other, and by their 

 coxal cavaties being open behind, excei)t in Cistelidas where they are 

 slightly closed. The larvae of all these insects are found under the bark 

 or in the decayed wood of trees which have been long dead. The per- 

 fect insects are generally found in the same situations, but some, especi- 

 ally the Cistelidrt', are often seen upon leaves or flowers. , 



The following are the families of bark-beetles : 



A. Thorax rouuded at the sides, or without a sharp lateral margin, uarrower behind 

 than in front, and narrower at base tlian tlic elj'tra. 

 Ji. Head gradually narrowed behind, and usually somewhat prolonged in front; 



last joint but one of tarsi slightly bilobed O^^demerid^. 



BB. Head not narrowed behind; sometimes prolonged in front into a snout; 



tarsi entire Pytiiid.e. 



A A. Thorax witli a lateral margin, not narrowed boliind, and usually as wide at 

 base as the elytra. 

 C. Maxillary palpi terminating in a hatchet-shaped joint; claws serrate: 



ClSTELID^E. 



C C. Maxillary palpi usually long and pendulous, with all their joints more 

 or less enlarged ; claws simple Met.andkyid.e. 



Family XLIX. ffiDEMEKID^. 



A small family of heteromerous beetles, with elongate, narrow bodies, 

 the head and thorax somewhat narrower than the elytra, ami rather 

 long filiform antennae. The elytra in some of the foreign species are 

 narrowed and separated behind. Our most conspicuous species is the 

 Nacerdes meJanura, which is more than half an inch in length, of a yel- 

 lowish-brown color, with the elytra tii)ped with black. 



