244. PROCEEDINGS OF THE NATIONAL MUSEUM Vou. 113 
Discussion: Dietz (1894) considered S. silaceus Casey to be con- 
specific with S. imbricatus Casey, but after comparing the lectotype 
specimens, and other examples, of the two species, the writer has con- 
cluded that they are two very distinct species. In S. imbricatus, the 
sides of the prothorax are nearly parallel, the humeri are very promi- 
nent, the elytra are rather elongate, the rostrum of the female is much 
longer and smoother before the antennal insertions than that of the 
male, and the scales are either grayish brown or white. None of the 
last statements could be said to be true of S. silaceus (see the descrip- 
tion). In addition there is no pair of sclerotized plates attached to the 
internal sac of the male genitalia in S. imbricatus, but there is such a 
pair of plates on the internal sac in S. szlaceus. 
S. silaceus resembles S. pusillus Dietz in respect to size, body shape 
and proportions, punctation of the prothorax and shape of male geni- 
talia, but when the two species are compared, it can be seen that the 
sides of the prothorax are more distinctly rounded in S. silaceus than 
in S. pusillus and that the scales of the elytra are yellowish brown or 
white in the former but are distinctly gray in the latter. 
Disrrisution: Records taken from the material examined indicate 
that the range of S. silaceus extends from the Gulf coastal plain in 
Texas across the southern portion of the Great Plains into the Southern 
Rocky Mountains and into the southern portion of the basin and 
range province. The following specimens were examined: 
ARIZONA: MARICOPACO.: Mesa, May13(USNM).  pimaco.: Tucson, Apr. 25, 30, 
May 6(USNM)._ prnauco.: Oracle, July 4(USNM). santa cruz co.: Nogales, 
Aug. 18 (USNM); Santa Rita Mountains, May 24 (USNM). 
New MExXICco: SAN MIGUEL Co.: Las Vegas, Aug. 12 (USNM). 
TEXAS: CAMERON co.: Brownsville (USNM). EL paso co.: Aug 22 (USNM). 
VAL VERDE CO.: Del Rio, 925 ft. (USNM). werssco.: Laredo, May 28 (USNM). 
Total specimens examined: 21. 
Smicronyx pusillus Dietz 
FIGuRE 66 
Smicronyz pusillus Dietz, Trans. Amer. Ent. Soc., vol. 21, pp. 141-142, 1894. 
Lectotype, here designated: Male, San Bernardino, California, Aug. 15, MCZ 
1899 (Dietz collection). 
Description: Rostra of both sexes black, stout, moderately curved; 
sparsely punctate, finely punctulate and sparsely squamose behind 
antennal insertions; distinctly striate dorsally from antennal insertions 
to near apex in male; not distinctly striate in female. Head black, 
surface finely punctulate and dull, sparsely squamose in front. Anten- 
nae black; scales narrow and white. Prothorax black, broadly round- 
ed at sides, slightly narrowed toward apex; disk sparsely punctate, 
interspaces dull, densely punctulate; scales pale gray, some elongate, 
