1873.J \-£u [Horn. 



surface generally, diverging from the tip of the sutural stria, a character 

 of frequent occurrence in Hydrobius. 

 Occurs from Canada to Georgia. 



P, ochraceus, Mels. Proc. Acad. II, p. 101 ; Lee. Proc. Acad. 1855, p. 

 371 ; simplex, Lee. New Species, p. 24. 



Oblong oval, equally narrowed in front and behind, pale piceo-testa- 

 ceous, vertex and middle of clypeus usually piceous, surface moderately 

 shining, rather coarsely punctured, the punctures of the thorax finer and 

 denser than those of the elytra. Body beneath black, legs piceous tarsi 

 paler. Length .14 inch ; 3.5 mm. 



Resembles nebulosus and reflexipennis but may be distinguished from 

 the former by the absence of prosternal carina and from the latter by the 

 very narrow crest of mesosternum which does not form an acute free angle. 

 P. simplex, Lee. is a small form differing only in size and in being some- 

 what smoother. 



Occurs from Massachusetts to Florida. 



P. reflexipennis, Zimm. Trans. Am. Ent. Soc. 1869, 250. 



Pale piceo-testaceous. Resembles the preceding species in all the 

 characters of the upper surface except that the head is never piceous. Body 

 beneath black. Femora at base piceous tibia} and tarsi pale testaceous. 

 Elytral margin especially at apex sub-explanate. Mesosternal crest 

 acute at tip and mucronate. Length .14-. 18 inch ; 3.5-4.5 mm. 



Specimens are from New Jersey and Delaware. 



P. consors, Lee. New Species, p. 24. 



Oblong, black, shining, finely and densely punctured, transversely 

 strongly convex, sides nearly vertical. Anterior edge of mesosternal crest 

 oblique. Sutural stria faint scarcely deeper at apex. Body beneath and 

 legs entirely black. Length ,28-.32 inch ; 7-8 mm. 



Louisiana. 



P, cinctus, Say (Rydrophilus) Long's Exped. 2. 276 ; Lee. Proc. Acad. 

 1855, p. 371 ; limbalis Mels. Proc. Acad. 2, p. 101. 



Broadly oval, black, shining, entire margin piceous, surface finely 

 punctulate. Mesosternal crest with lower margin horizontal, anterior 

 edge vertical, angle scarcely mucronate. Length .26 inch ; 6.5 mm. 

 Shorter and broader than the preceding species and resembling therefore 

 (Helochares) rotundatus, Say. 



Occurs from Canada westward to Kansas and southward to Georgia. 



The four species which follow are all so clearly allied that nothing in 

 addition to the characters in the synoptic table need be given. They are 

 feebly or moderately convex, surface punctulate always more densely and 

 finely on the thorax than the elytra. In color individual variations occur 

 from testaceous to dark piceous in each species. 



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



The largest species of the series. The mesosternal crest is deeply sinu- 

 A. p. s.— VOL. XIII. Q 



