204 



COLEOPTERA OF NORTH AMERICA. 



Metasternum not advanced between the coxae, eyes entire (body less per- 

 fectly contractile) ; 

 Three outer joints of antennae very large. Dorcatoma. 



Antennae serrate, 11-jointed ; outer joints not larger. Xyletinus. 



In Eupactus and Tylistus the epistoma is separated from the 

 front by a deep line ; in the other two genera the line is quite 

 faint. The vacant space between the anterior legs in Eupactus, 

 which terminates in the emargination of the metasternum, is filled 

 in repose by the last joints of the antennae. The type of Tylistus 

 is Dorcatoma simile Say ; the mandibles in repose are applied 

 to the metasternum. 



Group II. — Anobia. 



In this group the mandibles are less dilated at base, and the 

 prothorax is deeply excavated beneath, for the protection of the 

 mouth, which in repose is received upon and between the anterior 

 legs, which are not contiguous at base. The contractile power is 

 less developed than in the preceding group, and the species are 

 oblong or sub-cylindrical in form. The antennas are 10- or 11- 

 jointed, and vary in form, according to the genera. The elytra 

 are always punctured in rows ; the plates of the hind coxae are 

 narrow, and the last joint of the tarsi is broad and depressed. 



Our genera are : — 



Antennae 11-jointed; 

 Mesosternum deeply and broadly excavated ; 

 Groove extending upon the metasternum ; 



Antennae serrate, outer joints not larger. Trypopitys. 



Antennae with the joints 9 — 11 much longer. Coelostethus. 



Groove not extending upon the metasternum ; antennae with the joints 

 9 — 11 much longer ; 

 Thighs not clavate. Hemicoelus. 



Thighs strongly clavate. Ptinodes. 



Mesosternum fiat or scarcely concave ; antennae with the joints 9—11 

 much longer. 

 Anterior coxae widely separated ; 



Claws with a large broad tooth. Trichodesma. 



Claws slightly dilated at base. Nicobium. 



Anterior coxae nearly contiguous. Anobium. 



Antennae 10-jointed, joints 4 — 7 very short, 8 — 10 very long ; 

 Mesosternum not protuberant ; 



Anterior coxae nearly contiguous. Oligomerus. 



Anterior coxae widely separated. Cacotemnus. 



Mesosternum dilated into a large plate. Petalium. 



