284 G. H. HORN, M. D. 



* Synopsis of APHODIINI of the United States. 

 BY GEO. H. HORN, M .D. 



OXYOMUS, Casteln. 



0. opacifrons, n. sp. — Oblong; piceous black, feebly shining. Head moder- 

 ately convex opaque, sparsely and finely punctured; ciypeus very feebly 

 emarginate. Thorax one half broader than long, convex, sides feebly rounded 

 hind angles nearly rectangular, base strongly rounded and without marginal 

 line, surface coarsely punctured, more sparsely in front, and with a moderately 

 deep sulcus at posterior portion of median line. Elytra one-half longer than 

 wide, sides feebly rounded, surface with nine acute costal (not counting the 

 sutural) of which the first, second, fourth, sixth and eighth are entire ; intervals 

 deeply concave and with large punctures closely placed. Body beneath°and 

 femora coarsely punctured. Length .12 inch; 3 mm. 



This is the smallest Aphodiide, in our fauna and may be very easily 

 known by the fjjeneric characters and the description above given. 

 Occurs rarely in the Middle States. 



AT^ENITIS, Harold. 



Our species of this genus are less numerous than those of ApJwdtuSj 

 although much more so than any of the genera which follow. Several 

 species are widely diffused, extending their limits from extreme north- 

 ern regions in our continent southwardly in all intervening territory to 

 Buenos Ayres, and Chili. The sexes are very troublesome to distin- 

 guish and no characters are presented in Atfienius, that will bear com. 

 parison with some of the very remarkable ones already observed in 

 many Aphodini. 



The following table presents all the species known to me. 



Ciypeus emarginate at middle, broadly rounded on each side, never dentate 

 nor subangulate. 

 Opaque species; thorax without marginal line at base. 



Elytral interspaces flat imbricatus. 



Elytral interspaces elevated, alternately longer alternatus. 



Shining species; with basal marginal line. 

 Color black or piceous. 



piytral interspaces flat, strise shallow robustus. 



Elytral interspaces moderately or very convex. 



Thorax evenly and densely punctured gracilis. 



Thorax unequally and irregularly punctured. 

 Metathorax very coarsely punctured. 



Elytral intervals punctured oblongus. 



* Being a continuation of paper entitled " Synopsis of the Species of APHO- 

 DIUS and DIALYTES of the United States," in Trans. Am. Ent. Soc. 1870 

 (q. v.) 



