490 Coleopterological Notices, V, 



three-fourths as wide, convex ; eyes moderate, near the base ; supra-ocular 

 foveae at some distance from the eye ; spicules very small ; antennae one-half 

 as long as the body, the basal joint stout, compressed beneath, two to five 

 longer than wide, six and seven quadrate, eighth wider than long, club large, 

 abrupt ; palpi long but stout, the last two joints pubescent with erect, minutely 

 capitulate setae and smaller subrecumbent hairs. Prothorax one-fourth wider 

 than long, widest at the middle where the sides are rather broadly rounded, 

 strongly convergent and sinuate toward the apex, which is two-thirds as wide 

 as the base ; subbasal fovea at each side rather large, the surface before it 

 somewhat broadly flattened. Elytra not quite as long as wide, scarcely as 

 long as the head and prothorax ; sides broadly, evenly arcuate throughout ; 

 humeri angulate and distinctly exposed, the humeral width fully three-fourths 

 of the subapical ; discal impression feeble, traceable to the middle. Abdomen 

 rather narrower and much shorter than the elytra. Length 1.5-1.6 mm.; 

 width 0.65-0.7 mm. 



Indiana ; Iowa. 



The two type specimens are females, which leads me to think that 

 the modiBcations of the first antennal joint in this genus may possi- 

 bly be to some extent asexual. 



TYCHUS Leach. 



In both Tychus and Cylindrarctus the sexual characters are nearly 

 as in Arthmius, the male having a small flat horizontal pygidium 

 behind the last ventral segment ; in the female the pygidium is 

 wanting, and the last ventral is more or less acutely produced in 

 the middle at apex. In these genera the first antennal joint is 

 attached to the under side of the frontal tubercles as in Pselaphus, 

 and the antennal cavities are very large and extremely deep, so that 

 they meet internally, being separated — in an oval area — only by a 

 thin transparent membrane. In both genera the upper surface of 

 the head has a small nude puncture, more or less near the anterior 

 part of the eye, and, between this and the frontal tubercles on each 

 side, a small erect spicule which is a very constant peculiarity 

 throughout. The antennal tubercles are large, approximate, and 

 separated by a short longitudinal canal. 



Our species are comparatively few in number, and none have yet 

 been observed possessing sexual modifications of the antennsB ; they 

 are minute, closely allied among themselves, and may be distin- 

 guished by the following characters : — 



