242 GEO. H. HORN. 



least one of the claws of the front tarsus distinctly toothed at base, 

 and in reflexipennis, diffusus and HamiUoni, the tooth is so large, and 

 in the last two so everted, that when the tarsus is seen directly from 

 above it seems tridactyle. As there are differences between nearly 

 all the species these will be more fully alluded to in their proper 

 place. 



Failure to notice the sexual characters led me, in 1873, to attach 

 too great importance to the form of the mesosternal lamina in the 

 separation of species. It is now known that the form of tlie lamina 

 is by no means constant in a series of specimens, nor is it of the same 

 form in the sexes. As a rule the males have the more prominent 

 lamina, the angle more prominent and the anterior edge more ob- 

 lique, while in the female the angle approaches more nearly a right 

 angle by the front edge being more nearly vertical. This is well 

 illustrated in the various forms observed in nehuloms. Profile views 

 are given of all the laminae drawn in every instance from the male. 



In those testaceous species with black head it will be observed that 

 the male has usually the anterior half of the head pale while in the 

 female the head is entirely piceous, except a triangular space before 

 each eye. 



All our species are entirely piceous and opaque beneath, the femora 

 are also opaque, densely punctured and pubescent, except for a short 

 distance at apex. 



The differences in the structure of the maxillary palpi afford the 

 means of subdividing the genus into two primary groups, as follows : 



Last two joiuts of maxillary palpi nearly equal in length. ..S. G. ENOCHRUS. 

 Last joint always shorter than the third S. G. PHILYDRUS. 



ENOCHRUS Thonis. 



This subgenus contains in our fauna three species, two of which 

 have the prosternum longitudinally carinate. 



Prosternum carinate. 



Entirely piceous, tarsi alone pale ; anterior claw of male slightly angnlate at 



base cariiiatus. 



Thorax, elytra, tibiae and tarsi pale rufo-testaceous, head and under side pice- 

 ous; anterior claw of male very distinctly toothed Fiieatus. 



Prosternum not carinate. 



Piceous, sides of head and thorax pale CiispiUatiiS. 



But one other species, hicolor Payk, of Northern Europe is known ; 

 our species are from the Western side of the continent and still 

 further illustrate the relationship, which has already been alluded to, 

 between the faun?e of the Pacific region and Europe. 



