Horn.] 160 [Feb. 21, 



ate in front, the angle very acute and prominent forward and not mucro- 

 nate as in the next species. Length .18- .24 inch ; 4.5-6 mm. 



Nebraska. 



P. fuscus, Motsch. Bull. Mosc. 1859, III, p. 178. 



Smaller than the preceding aud with rather finer punctuation, differs 

 principally in the form of the mesosternal crest, which is more acute at 

 tip and with the point strongly bent downwards. Length .16-. 18 inch ; 

 4-4.5 mm. 



San Francisco, California. 



P. perplexus, Lee. Proc. Acad. 1855, p. 371. 



The mesosternal crest in this and the next species is not sinuate on the 

 front edge and the angle formed by the union of that edge and the lower, 

 is broad and not acute as in most of the species which precede. As com- 

 pared with the other three species of this small group the present one is 

 usually more elongate and transversely more convex, and when perfectly 

 mature the color is almost entirely black, with merely a narrow piceous 

 limb as in ductus. 



Length .17-.20 ; 4,5-5 mm. 



This species is of almost universal distribution in our country extend- 

 ing from the Middle States to Florida and westward to California. 



P. latiusculus, Motsch. Bull. MoSc. 1859, p. 178. 



Broader and more depressed than any species of the group, the breadth 

 being always greater than half the width. The appearance of the species 

 recalls fuscus. The mesosternal crest is similar to that of the preceding 

 species. Length .18 inch ; 4.5 mm. 



California. 



P. obtushisculus, Motsch. loc. cit. p. 179. 

 Unknown. California. 



The second section Helochares has been by some students retained as a 

 genus separate from Philliydrus, a view which can scarcely be adopted 

 with our species, as the tendency to the obliteration of the carina is very 

 evident in nebulosus, while several in the present section have a trans- 

 verse ridge more or less elevated. The species are as follows : 

 Prosternum carinate. 



Elytra with ten entire, punctured stria? maculicollis. 



Prosternum not carinate. 



Elytra entirely or in part striate. 



Form very broadly oval ; entirely striate punctatostrint'ix 



Form elongate oval ; striate at the sides imbellis. 



Elytra not striate or with mere traces at apex. 



Elytra! punctures coarser toward the apex. . . . lacustris, fimbriatus. 

 Elytral punctures obliterated toward apex .... rotundus. 



P. maculicollis, Mels. Ann. Sc. Phys. Nat. Lyon. 7, 379 ; Lee. Proc. 

 Acad. 1855, 370. 



Oblong oval, more attenuate in front, piceous, margin paler, nioder- 



