PLATYPSYLUDAE. 73 



Tribe IV.— SPHiERlDIIlVI. 



Small terrestrial species, of an oval, convex, or hemispherical 

 form, living in the excrements of herbivorous mammals; the color 

 is usually black, with the elytra frequently spotted or marg-ined 

 with vellow; the elytra have ten rows of punctures or striie, but 

 in Cyclonotum are entirely without striae. Our species of Cercyon 

 are not yet properly investigated ; several of them have been 

 imported from Europe. 



Maxillse with lobes coriaceous, or submenibranous ; antennaj 

 9-jointed in our genera; second joint of maxillary palpi thick- 

 ened; legs not natatorial; first joint of middle and posterior tarsi 

 elongated. 



Except SphiEridium,* all tlie known genera of this tribe have 

 been found in the United States. They are distinguished as 

 follows : — 



Mesosteruuin narrow ; 



Scutel elongate ; pygidium visible. ^Sphaeridium. 

 Scutel equilateral ; pygidium covered 



Metasternum produced in front. Dactylosternum. 



Metasternum not produced. Cercyon. 



Mesosternum and uietasternum connate, with a ridge produced in 



front. Cyclonotum. 



Mesosternum very wide; 



Prothorax margined. Megasternum. 



Prothorax not margined. Cryptopleurum. 



Fam. VIIL— platypsyllidae. 



Mentum large, transverse flat, emarginate in front, with 

 rounded angles; sides rounded; base strongly trilobed, the 

 lateral lobes are very large, flat, subtriangular processes; 

 obliquely rounded on the outer side, straight on the inner 

 side, gradually narrowed behind, and rounded at the tip; 

 these processes are nearly as long as the middle lobe, sepa- 

 rated from it by narrow fissures, and, like it, project far 



* A spo(!imen of the European SpJia-ridiiini sraraba'.onle.'i has been found in 

 Canada. The species is undoubtedly introduced, and accidental in occui- 

 rence. It is described by Beauvois Tinder the name S. rrnHttnin. The 

 genus differs from Cercyon by the antenna; having only eight joints, and 

 by the elongate scutel. 



