170 GEO. H. HORN, M. D. 



to the granular, resulting from a gradual breaking up of tlie intervals and 

 the formation of elongated tubercles. This change begins at the sides 

 and declivity of the elytra and finally invades the entire surface. 



The species are not numerous but not readily distinguishable by 

 description, the following characters seem to be the most constant. 



Basal impressions of thorax broad and deep and with coarse deep punctures 

 more or less confluent. 



Elytra oboval, sculpture decidedly granular niticlicollis. 



Basal impressions of thorax linear and not very deep, the punctures rather 

 fine and not confluent. 



Hind angles of prothorax very obtuse stenostonins. 



Hind angles of prothorax well defined cauadeusis. 



C (Sphseroderus) nitidicollis Chev. Guer. Icon. Reque An. p. 24, pi. 7, 

 fig. 1, a — c; niagarensis Cast. Ann. Fr. 1832, p. 390; Lacord. Genera Atlas, pi. 2, 

 fig. S; Brevoorti Lee. Ann. Lye. iv, p. 443; Schaumi Chaud. Bull. Mosc. 1861, ii, 

 p. 499; granulosus Chaud. loc. cit. p. 497; palpalis Motsch. Bull. Mosc. 1865, iv. 

 p. 312. — Moderately elongate, surface with cupreous or violet tinge. Head 

 feebly elongate, gense moderately dilated concealing the base of the maxillfe. 

 Thorax broader than long, base and apex equal, sides arcuate, slightly oblique 

 posteriorly, hind angles obtusely rounded, margin with a thickened bead, disc 

 convex, anterior and median impressions feeble, basal transverse impression 

 moderately deep, angular impressions broad and triangular, these and the 

 transverse impression coarsely and deej)Iy punctured. Elytra oval, usually 

 broader behind the middle, surface variably sculptured, iuflexed portion coarsely 

 punctate. Length .48 — .64 inch ; 12 — 16 mm. 



The elytral sculpture varies so that it is almost impossible to give 

 any general description. 



var. Brevoorti Lee. — -Elytra at base deeply striate, strife coarsely crenately 

 punctured, intervals at sides and apex broken into numerous granules and 

 elongate tubercles. 



var. nitidicollis Chev. — Striae of elytra almost entirely wanting, the inter- 

 vals tuberculate, the tubercles forming three rows of larger ones between 

 the smaller rows and the entire surface of the elytra with numerous small 

 granules. 



In all the species of this subgenus the sculpture tends to vary from 

 the striate to the tuberculate, and thus to reproduce the characters of 

 the true Cychrus form as represented in our fauna by tuherculatus. 



On comparing this species with stenosfomus there will not be found 

 any great differences of general form ; in the present the elytra are apt 

 to be wider behind the middle, but this is by no means constant. The 

 only character which seems to me to define the two is found in the 

 fact that in this the impressions of the hind angles of the thorax are 

 broad, deep and coarsely punctured, those of stenostomus are linear, 

 less deep and scarcely at all punctate. 



Occurs from the Hudson's Bay region to northern Virginia. 



