OSTEN SACKEN ON WESTERN DIPTERA. 253 



Two male specimens from California (one of them from the Shasta 

 district, H. Edwards) belong apparently to the same species, and are 

 nearly of the size of the larger ones from Cheyenne. 



Finally, a female from Nantucket, Mass. (caught over sandy soil, 

 middle of September, by Mr. S. H. Scudder), is larger thau the females 

 from Cheyenne, measuring nearly 10 mm ; the proboscis is a little shorter 

 and there is more yellowish pile in the beard around the antennae ; in 

 other respects, the agreement is perfect. 



A. barbatus is therefore either a species with a very wide distribution , 

 or else there are several closely allied species, which, with the material 

 before me, I am unable to distinguish. The European species of this 

 group (A. nitidulus, etc.) are also remarkably like A. barbatus. 



Systcechus. 



A difficult genus on account of the great resemblance of the specie s 

 and the apparent scarcity of distinctive characters of an absolute and 

 more than comparative value. Systcechus is very common in the West, 

 but occurs also in the Southern States. I have seen only one specimen 

 from the Northeastern and Middle States, which I took near Alexandria 

 Bay, Saint Lawrence River. 



1. Systcechus vulgaris Loew,Centur.,iv, 52 (Nebraska ; Dr.Hayden). 

 A common species in Colorado, about Denver, Manitou, etc., July, August 

 (P. E. Uhler and myself); also in Utah (a male from Salt Lake City, 

 July 21, by A. S. Packard). The fulvous hairs on the face are often more 

 abundant than Dr. Loew's wording implies ; in the female, they extend 

 to the front, especially along the eyes. 



A female specimen which I caught near Alexandria Bay, N. Y., on 

 Saint Lawrence Eiver, is smaller, but does not, in other respects, differ 

 from S. vulgaris. 



I have two males and two females from Illinois (Le Baron) and Den- 

 nison, Crawford County, Iowa (Allen; July, 1867), which, instead of the 

 usual pale yellow color of S. vulgaris, are of a decidedly reddish-yellow, 

 almost rufous ; in outline, they seem' to me broader thau S. vulgaris, and 

 may belong to a different species. 



2. Systcechus solitus Walker, List, etc., ii, 288 (Bombylius). — Flor- 

 ida. As suspected by Dr. Loew (Centur., iv, 52), this is a Systcechus. 

 I have a specimen from Capron, Fla. (Messrs. Hubbard and Schwarz, in 

 April), which answers the description. It differs from S. vulgaris in 

 having the tarsi and the ends of front and hind tibiae black ; the spines 

 on femora and tibiae are of the same color. I do not discover any other 

 difference. 



3. Systcechus candid ulus Loew, Centur., iv, 51 (Wisconsin). — Be- 

 sides the whitish pile covering the whole body, this species is easily dis- 

 tinguished by its longer proboscis and more hyaline wings, with paler 

 veins; the pile on the face and front is black without admixture, and 



