Aw 
1878. ] o47 |Horn. 
genera. Here there is no frontal margin at all, and the antenné are ex- 
posed at base. 
Our species, with one exception, occur from the regions west of the Rocky 
Mountains, while the reverse is the case in Bostrichus. They are distin- 
guished in the following manner : 
Thorax with distinct hind angles.................+. Socrae dhe eee ta Ge 
Thorax with hind angles not prominent. 
Declivity of elytra distinctly margined at tip.......... ...punctipennis. 
Declivity not margined. 
Surface with sparse recumbent pubescence...... Josh er Dicaldatus. 
Surface with moderately long hairs. Form more slender....... teres. 
A. fortis Lec. New Species, 1866. p. 101. 
Cylindrical, robust, piceous black, shining. Thorax a little broader than 
long, apex with two hook-like processes pubescent at tip, in front roughly 
granulate, toward the anterior angles serrate, posteriorly densely granu- 
late, smoother near the hind angles which are prominent. Elytra coarsely 
substriately punctured, declivity gradually convex, not margined nor cal- 
lous. Body beneath sparsely punctulate, scarcely at all pubescent, Length 
.88-.68 inch ; 9.5-17 mm. 
This species is abundantly distinct from punetipennis by the prominent 
hind angles of the thorax, the form of the declivity and the almost entire 
absence of pubescence beneath. Crotch appears to have considered it the 
female of the next species, and for that reason omitted it from the Check 
List. I cannot convince myself that so many differences are sexual only. 
Occurs from St. George, Utah to Arizona and Peninsula of California. 
A. punctipennis Lec. (Apate) Proc. Acad., 1858, p. 73. 
Cylindrica!, robust, piceous black, shining. Thorax as long as wide an- 
teriorly with two hook-like processes (not pubescent at tip), anterior face 
of thorax roughly granulate, at the sides serrate, posteriorly smoother 
granulations flattened, not prominent, hind angles not distinct. Elytra 
subseriately coarsely punctured, declivity slightly flattened, on each side 
two elongate callosities; at tip for a short distance acutely margined. 
Body beneath moderately densely punctate and clothed with fulvous pubes- 
cence. Abdomen densely punctulate with a few very large punctures in- 
termixed, surface densely fulvo-pubescent. Length .46-.54 inch; 11.5- 
13.5 mm. 
Occurs from Texas and Utah to New Mexico, Arizona, California, 
Peninsula California and Mexico. 
A. bicaudatus Say, (Apate) Journ. Acad. III, p. 320; aspericollis 
Germ. Ins. Spec. nov., p. 258; hamatus Fab. forte, Ent. Syst. i, 2, p. 360; 
Syst. El. II, p. 380. 
Cylindrical, moderately elongate, piceous brown, sparsely clothed with 
recumbent pubescence. Thorax as in punctipennis but with the hook-like 
processes smaller. Elytra moderately coarsely irregularly punctured, de- 
clivity oblique coarsely cribrate. Body beneath moderately densely punc- 
