412 Trans. Acad. Sci. of St. Louis. 



type prevailing in Gyrohypnus and XanthoUnus, the gular 

 sutures as in the former of those genera and the medial 

 and ocular frontal grooves are all evident, although the me- 

 dian pair are much shorter and feebler than in Gyrohypnus. 

 The neck is notably narrower than in that genus, being but 

 little more than a fourth as wide as the head. The punctures 

 are usually small but distinct and rather close-set on the 

 head, those of the elytra being fine and evenly spaced, though 

 irregularly arranged throughout. The remarkable sexual 

 characters of the female have been alluded to by the writer 

 (Bull. Cal. Acad. Sci., 1886, p.* 261 and plate), that sex 

 having the sixth ventral prolonged into a very slender spine 

 curving upward beyond the tip of the abdomen in at least 

 two species alluded to below, and, leading up to this peculiar 

 formation, it may be stated that in the genus NematolinuSy 

 described above, as well as in Hesperolinus piceus, the female 

 has the tip of the sixth ventral strongly and acutely angulate, 

 it being broadly rounded or parabolic in the male, as is also 

 the case in the present genus as a rule. The females seem to 

 be much less abundant than the males. The species of 

 Hesperolinus are rather numerous on the Pacific coast, those 

 at hand being separable by the following characters : — 



Second antenaal joint subequal io length to the third, both distinctly 

 elongated; female usually with the sixth ventral prolonged into a 

 slender spine 2 



Second antennal joint evidently longer than the third, elongate, the latter 

 sometimes much abbreviated; female having the sixth ventral slightly 

 prolonged and acutely angulate at the middle, at least in piceus 6 



2 — Male having the apex of the sixth ventral broadly subangulate, with 



the angle broadly rounded and not noticeably produced 3 



Male having the apex of the sixth ventral more or less narrowly and 

 strongly lobed in the middle, the lobe evenly rounded at tip 5 



3 _ Prothorax darii in color, black or blackish, always darker than the 



elytra. Body rather stout, subparallel, blackish -piceous in color, the 

 head black and the elytra generally slightly paler, piceous; antennae 

 dusky, the legs paler, rufous; integuments shining; head well devel- 

 oped, much longer than wide behind the antennae, the sides parallel 

 and nearly straight or feebly diverging basally, the angles broadly 

 rounded; punctures not very coarse but deep, close-set and conspicu- 

 ous, still denser toward the eyes, rather narrowly wanting along the 

 middle, smaller but close-set on the under surface and flanks, the con- 

 vex longitudinal post-ocular line distinct; antennae but little longer 



