226 COLEOPTERA OF NORTH AMERICA. 



iind the last three joints dilated, very large, forming a loose 

 club, much longer than the preceding portion. Tlie prosteruum 

 is very short and broad, and separates widely the front coxae, 

 which are small, conical, and ascend perpendicularly the sides of 

 the cavity. The middle legs are received in deep excavations of 

 the meso- and metasternum, the tarsi rest in small deep grooves 

 behind the metasternal process, and the knees in subhumeral 

 cavities of the cpipleurse. The first ventral segment is deeply 

 excavated, each side, for the reception of the hind legs; the knees 

 are not received in epipleural fovcfe. The ventral segments seem 

 disposed to become connate. 



Our genera are three, distinguished as follows: — 



Elytra not striate. 



Prosternum produced behind into two long horns, metasternal lobe 

 narrowed at base. Dorcatoma. 



Prosternum broadly truncate behind, metasternal lobe short. 



Caenocara. 

 Elytra striate ; metasternum with large anterior lobe not narrovved be- 

 hind. Byrrhodes. 



Four species of Dorcatoma occur in the Atlantic region : and 

 five of CaMiocara, one in California, the others in the Atlantic 

 region; Byrrhodes in Florida. 



Tribe II.— PTILIRTIIVI. 



The head is deflexed, less retractile than in the preceding 

 groups; the eyes are rounded and distant from the thorax in the 

 female, but larger in the male; the antennte are 11-jointed, ser- 

 rate in the female, and branched in the male. The last joint of 

 .the palpi is oval. The thorax is convex, rounded in front, pro- 

 jecting the head, and granulate with small tubercles towards the 

 apex; it is not excavated beneath, and the prosternum is moder- 

 ately developed in front of the coxae, which are large and contigu- 

 ous. The plates of the hind coxas are exceedingly narrow. The 

 legs are moderately retractile, and the first joint of the tarsi is 

 longer than the second. 



Antennae of '^ flabellate ; eyes small. Ptilinus. 



Antennae of ^ pectinate; eyes large. Euceratocerus. 



Ptilinu-s is represented on both coasts of our country; it ap- 

 proaches closely in form certain members of the tribe of the 

 next sub-family, and estal)lishes a transition between the two. A 

 slight relation with Melasis of the sub-fnniily Eiicnemiua! is like- 

 wise quite obvious ; Euceratocerus occurs in 'J'exas, 



