4 PROCEEDINGS OF THE NATIONAL MUSEUM vol.82 



These groups of species have certain characters in common. The 

 head is inserted as far as the eyes, and has a fovea on the vertex 

 on each side near the eye, the fovea being usually surrounded to a 

 greater or lesser extent with punctures. The sculpture of the head 

 offers one of the best characters for separating the groups of species. 

 In the alteniata group, coarse punctures not only surround the fovea 

 but usually extend over most of the occiput and vertex; in the 

 discoidea group, on the other hand, a single large pit or fovea on 

 each side is often the only trace of punctation. In some species, such 

 as xanthomelas, the punctures are arranged to form a furrow extend- 

 ing from the fovea to the frontal tubercles. These tubercles are also, 

 somewhat variable. They are distinctly defined in most species, and 

 in some groups, as the alternata group, they are somewhat swollen, 

 while in latifrons they are so flat as to; be scarcely distinct. The area 

 between the antennal sockets tends to be carinate, although not much 

 produced. In many species, as in triangularis, this carina is quite 

 acute, while in others, as in tenmcomis and funerea, the interanten- 

 nal area is broad and flat. The carina extends well down the lower 

 front, joining the frontal margin. The antennae, differing some- 

 Avhat in length according to the sex, those of the male being a little 

 longer, usually do not extend beyond the middle of the elytra, and 

 the third joint is shorter than or subequal to the fourth. In the 

 female, the eighth, ninth, and tenth antennal joints are slightly 

 shorter and slenderer than in the male. 



The shape of the prothorax differs greatly in different groups. 

 In general, the prothorax is nearly the same width as the elytra, 

 approximately twice as broad as long, sometimes more, and occasion- 

 ally a little less. It is slightly narrowed anteriorly with a more or 

 less arcuate, narrow, sharp-edged, lateral margin, much narrower 

 than in Oedionychis. The basal margin is somewhat sinuate, with 

 the hind angles obliquely truncate. In some groups of species, as 

 the pensylv arnica and alternata groups, the pronotum is not very 

 convex, and there are lateral callosities and a slight median basal 

 depression, while in others, as the discoidea, and fumata groups, the 

 pronotum is smooth, convex, and without depressions. 



The elytra are either oblong with parallel sides or oval with 

 rounded sides. The humeri vary in prominence, and are often 

 marked by a short sulcus on the inner side, referred to in the descrip- 

 tions of the species in this paper as an intrahumeral sulcus or depres- 

 sion. In the fensylvanica and alternata groups, there is a distinct 

 tendency toward elytral ridging in the female, the costae sometimes 

 extending from the humeri nearly to the apex. There is always a 

 narrow lateral explanate margin, not extending to the apex, and 

 beneath, the epipleura gradually narrow to the apex. The elytra 

 are not striate, but confusedly and never very coarsely punctate. 



