4 V.S. NATIONAL MUSEUM BULLETIN 290 



bear distinct pubescence on the dorsal surface. The species basalis 

 Suffrian, mucoreus Leconte, and lunatus, new species, have pubescence 

 on both the pronotum and elytra; puhicollis Linell has pubescence 

 only on the pronotum. The pubescence of the dorsal surface is rather 

 short and not dense; it somewhat obscures the surface. 



Shape: All the species are more or less compact, cylindrical, and 

 blunt on each end, and there is no great variation in the general shape. 

 The most elongate species is atrofasciatus Jacoby, up to 2.0 times as 

 long as wide. Most species range from 1.6 to 1.8 times as long as wide. 

 In the great majority of the species, the pronotal profile is more or 

 less evenly rounded from front to back. In only two species {gibbicollis 

 Haldeman and aulicus Haldeman), the pronotum is slightly to 

 distinctly bulging at its center, and the outline of the pronotum is 

 thus more gibbous than usual. 



Head: The head can best be described as disklike; it is flat anteriorly 

 and inserted into the thorax. When seen anteriorly, it is almost circular, 

 and its frontal plane is nearly or quite parallel to that of the anterior 

 margin of the prothorax. It fits tightly into the anterior cavity of the 

 thorax and is either concealed or nearly concealed from a dorsal view. 

 The surface is alutaceous to smooth and usually bears rather large, 

 distinct punctation. The vertex often bears a short coronal suture or 

 slight depression and frequently is more darkly pigmented than the 

 remainder of the head. The eyes form the lateral margins of the head 

 and are elongate reniform when seen anteriorly; they do not bulge 

 from the head surface (from a dorsal view they do bulge somewhat), 

 and the facets are small. The eyes do not reach the mandibles at their 

 lower margin, and they are distinctly separated at their upper margin. 

 The clypeus is large and distinct, and its basal suture is usually 

 distinct and is located between the bases of the antennae. The lateral 

 margins are distinct and usually diverging so the clypeus is generally 

 broader apically than basally. The apical margin of the clypeus (the 

 point of insertion of the labrum) is inwardly arcuate and sometimes 

 bears pubescence. The labrum is rather broadly tab-shaped, generally 

 broader than long, and has rounded corners. It frequently bears a 

 transverse row of anteriorly directed hairs before the apex. The 

 maxillary palpi are 3-segmented, short, and more or less stout; the 

 labial palpi are 2-segmented and similar to the maxillary palpi in 

 form. 



Antennae: Each antenna is inserted at a basal corner of the clypeus; 

 the points of insertion are separated by about the length of the first 

 antennal segment and are distant from the eyes by about the hori- 

 zontal diameter of an eye or a little less. The antennae are 11-seg- 

 mented, are generally over one-half to nearly as long as the body, and 

 are longer in the male than in the female. The first segment is the 



