278 
GEO. H. HORN, M. I). 
The species described by Gory are barely recognizable, and the 
figures give but little aid. He seems not to have known of the 
species described by Say, or else purposely disregarded them. 
It being veiy evident that the unsatisfactory work ])reviously done 
with our species w'as due to insufficient material, and the neglect of 
an examination of the sexual characters, no attemi)t has been made 
by me to record my observations until reasonably full series had been 
obtained with the sexes of each species represented. In the following 
pages but one species is represented by a single specimen, and of 
about four others two of each have been examined. 
As a general rule, our species are .not marked by any great surface 
irregularities, such as deej) thoracic depressions and strongly elevated 
elytral costte. The only exceptions aie cavaius and Couesii, the 
former being represented in Mexico and the other may also be. At 
ti]) the elytra are simjdy acute or rounded, never divergent, and 
variously formed as in many of the INIexican species. The colors 
are never very brilliant, nor is the ornamentation by pubescent spots 
very striking. The monotonous aspect of our species has com])elled 
a search for structural characters wdth very encouraging results, for 
with such characters, the limits of species may be more accurately 
defined notwithstanding any variation which may occur. 
In order that the systematic portion of this work may be the better 
understood, the various portions of the body showing important 
modifications will be reviewed consecutively. 
Antenna. —The form of these organs seems to have been entirely 
neglected. In some species the antenme are slender and long (PI. 
viii, figs. ]1-13), in others short and comparatively stout (PI. viii, 
figs. 12-14), in the former case the joints are longer than wide, and 
in the latter as wide, or even wider than long. The most im])or- 
tant modification observed is in the mode of their serration. By 
far the larger number of our species have the antennce serrate be- 
ginning wdth the fourth joint (PI. viii, figs. 11, 12); in the others 
the serration begins at the fifth joint (PI. viii, figs. 13, 14). There 
may be at times a (juestion wdth those who study this character for 
the first time and in some species it might be difficult to determine 
to which series it should be referred, but whenever the fourth joint 
resembles the fifth more nearly than it does the third, the species 
belongs to the first series, but when the third and fourth joints are 
similarly cylindrical then the species belongs to the second series. 
