The Pselaphid.'E of North America. 245 



legs, antenna; and palpi reddish-brown. Club of the fourth 

 antennal joint longer than the peduncle. Length, 1.8 mm. 



Besides the difference in size, form and color of the last 

 palpal joint, this species differs from P. erichsonii m the pro- 

 thorax being more convex at sides, and thicker, the elytra less 

 depressed on each side of the sutural lines, the interval not 

 dilated behind the middle, more convex from base to tip, and 

 the first dorsal segment more depressed at the base. The 

 males of both this and the preceding species have the middle 

 of the postpectus angularly impressed lengtlivvise. 



Habitat. Mississippi Valley from Iowa to Louisiana. 



Tychus, Leach. 

 The characters given in the synopsis of genera will suf- 

 ficiently distinguish this genus. 



TABLE OF SPECIES. 

 ii Elytra depressed, prothorax without median basal puncture, sutural lines 

 parallel. 



Palpi with the second, third and fourth joints nearly equal in 

 length. Color testaceous. Length, 1.17 mm. longipalpus. 



1 8 Elytra more convex, sutural lines arcuate. 



2^ Base of pronotum with five punctures; basal dorsal segment not longer, 

 third palpal joint triangular, shorter than the fourth Vertex with 

 two punctures. 

 3> Black with red extremities. Antennal joints 3-6 quadrate, 7-10 trans- 

 verse, rounded, obconical. --..-. minor. 

 3* Color testaceous or light brown, free angle of the third palpal joint 

 rounded. 



Elytra broadly convex, antennal joints oblong, slightly diminish- 

 ing in size, eighth smallest, the ninth twice as large, both sub- 

 globose, tenth transversely oval. $ with the anterior tro- 

 chanters spined. Length, 1.5 mm. - - - iestaceus. 

 Elytra very convex, antennal joints 8-10 transverse, 3-6 equal, 

 quadrate. Punctures on the vertex obsolete. Tarsi with a 

 thin second claw. Length, 1.3 mm. - - cognatus. 



2* Color, black with red extremities and elytra. Abdominal basal segment 



longer, base of pronotum punctured. 

 3' Head without the usual two punctures. 



Base of pronotum with three punctures, third palpal joint shorter 



than the fourth. Antennal joints 8-10 transverse. - tenellus. 



Base of pronotum with five punctures, third palpal joint fusiform, 



nearly as long as the fourth, which is cultiform. <J anterior 



trochanters and middle coxae spined. - - - puberulus. 



