50 COLEOPTERA OF NORTH AMERICA. 



Head separated from the thorax, movable. Silph^;. 



Head immersed in the thorax. Catopes. 



Group I.— Silphae. 



Insects of large or moderate size, living on carrion, compose 

 this group. Pteroloma (which includes Lyrosoma Mann.) and 

 Necrophilus occur only in the Pacific district; the other two 

 genera are found on both sides of the continent. 



Our genera are : — 



Antennae with ten apparent joints, club globose, 4-jointed. Necrophorus. 

 Antennae with eleven distinct joints ; 



Antennae clubbed,* tibiae armed with spines ; 



Third joint of antennae not longer than the second, shorter than the 



first. Silpha. 



Third joint of antennae as long as the first. Necrophilus. 



Antennae nearly filiform, tibiae not spinous. Pteroloma. 



Group II.— Catopes. 



Insects of small size and usually ovate form ; some live on car- 

 rion, others in fungi, others in ants' nests. The 8th joint of the 

 antennae is smaller than the 7th, except in Colon. 



Our genera are as follows : — 



Eyes wanting (anterior tarsi of 9 4-jointed.) Adelops. 



Eyes distinct ; 



Antennae serrate. Catoptrichus. 



Antennae clubbed ; 



Eighth joint of antennae small. Catops. 



Eighth joint of antennae larger than the seventh. Colon. 



Catoptrichus Frankenhaueseri, the type and only species 

 known, is found in Sitkha. Adelops hirtus, the only species yet 

 found in the United States, occurs in the Mammoth Cave, Ken- 

 tucky ; the other western caves will yet furnish other species. 



Sub-Tribe 2.'— Sphaeritini. 



This sub-tribe contains but a single genus, Sphserites, of which 

 but one species in Europe and another (S. glabratus Mann.) in 

 Russian America are known. The form is oblong oval, convex ; 



* In Necrophilus tenuicornis. however, the antennae are as slender as in 

 Pteroloma. 



