NO. 1487. NORTH AMERICAN DIGGER WASPS— FERNALD. 353 



long, slightly curved, with fine punctures and hairs; somewhat seri- 

 ceous, almost pubescent on its posterior part. 



Ahdoinen. — Rather ovoid, more pointed in front than behind; flat- 

 tened beneath, ver}^ coarsely grayish sericeous, both above and below; 

 posterior margins of the third, fourth, and fifth ventral plates emar- 

 ginate, this increasing posteriorly; terminal plates above and below 

 with scattered hairs, together quite conical in form. 



Wings. — Generally quite hyaline, sometimes more or less fuliginous 

 on the anterior and outer margins; generall}' with a strong yellow 

 tinge. 



Legs. — Black, ferruginous, or both colors, the coxa?, trochanters, 

 and basal half of the femora being black, as are frequently the outer 

 segments of the tarsi also; strongl}- sericeous, often pubescent in spots 

 on the coxffi and femora. 



Male. — Difl^ers from the female apparently, only in being more 

 strongly punctured, more generally pubescent, and in the usual sexual 

 characters. 



Length. — Females, 18-23 nlm. ; males, 13-22 mm. 



ChJorion {LsodontUi) costlpennis is a well known South and Central 

 American insect, having been captured in Brazil, Surinam, Guiana, 

 Guatemala, Panama, and Costa Rica. I have found no published 

 record of its capture in localities farther north, but have seen speci- 

 mens taken in Mexico (locality not given) and in Santo Domingo, 

 which bring it farther within the faunal limits of this paper. 



It is an exceedingly variable species as regards coloration, the 

 amount of pubesence, etc., which in some cases renders it diflicult of 

 determination. 



CHLORION (ISODONTIA) AZTECUM (Saussure). 



Spliex aztecus Saussure, Reise d. Novara, Hyni., 1867, p. 38. 



Isodontia azteca Patton, Proc. Bos. Soc. Nat. Hist., XX, 1880, p. o81. 



Sphex azteca Cameron, Biol. Centr.-Amer., Hym., II, 1889, p. 35, pi. in, figs. 9, 9a. 



Spliex robusiu Cameron, Biol. Centr.-Amer., Hym., II, 1889, p. 36, pi. iii, fig. 11. 



Sphex {Isodonlia) macrocephalus Fox, Ent. News, 1, 1890. p. 137. 



Sphex {Isodontia) aztecus Kohl, Ann. natur. Ilofmus. Wien, V, 1890, p. 385. 



Isodontia azteca Patton, Ent. News, IV, 1893, p. 302. 



Isodontia azteca Patton, Proc. Ent. Soc. Wash., Ill, 1894, p. 46. 



Sphex (Isodontia) viacrocephalus Kohl, Ann. natur. Hofmus. Wien, X, 1895, p. 50. 



Isodontia azteca H. Fernald, Can. Ent., XXXV, 1903, p. 269. 



Isodontia macrocephala H. Fernald, Can. Ent., XXXV, 1903, p. 269. 



Type of macrocephalus Fox, one female, slightly imperfect, in the col- 

 lection of the U. S. National Museum (Type Cat. No. 9906, U.S.N.M.), 

 from which the following description has been prepared: 



Female. — Large, robust, l)lack, without pubescence. Head large, 

 rather quadrangular when viewed from above; clypeus arched later- 

 ally, coarsely punctured, covered with long, coarse, black hairs; with 

 a median carina on its posterior portion; its anterior margin slighth' 



