OSTEN SACKEN.] 



ZOOLOGY DIPTERA. 563 



Anthrax^ sp. (Fair Play, Colo.), a single denuded and broken speci- 

 men, not unlike Eemipenthes seminigra, Lw., from Saskatchewan liiver 

 and Canada. 



Anthrax, sp., closely allied to A. fiavieeps, Lw. (Colorado Mountains^ 

 Pacific Slope.) I possess the same species from Utah Territory, select- 

 ed by Mr. Suck ley. 



Anthrax alcyon, Say (Colorado Mountains), a northwestern species 

 which I have from Saskatchewan, the Red River of the North, «&c. 



Anthrax, sp. (Twin Lake Creek and South Park), several indiffer- 

 ently-preserved species, which cannot be identified. 



Anthrax fulviana, Say (Twin Lake Creek ; Colorado Mountains), a 

 northwestern and northern species. (I have before me specimens from 

 Maine, Canada, Lake Superior, and Yukon River.) 



Systcechus candiduhcs, Loew (Colorado Plains), a western species, also 

 occurring in Illinois. 



Systcechus, sp. (Twin Lake Creek). 



Systoechus, sp. (Colorado Mountains), apparently identical with a 

 Californian species. 



Bomhylius {sensu strict), spec. (Twin Lake Creek and South Park). 



Family Stratiomyid^. 



Odontomyia w'grirostris, Lw. (Colorado Mountains, Pacific Slope), 

 was originally described from specimens caught in Northern Minnesota. 



Odontomyia, (between Clear Creek, and Colorado City), identical or 

 closely allied to 0. intermedia, Wied. C?), a species common in the North- 

 ern States. 



Stratiomyia nymphis. Walk. (Twin Lake Creek), was originally de- 

 scribed from specimens from the British possessions in North America. 



Family Asilid^. 



Laphria (Colorado Mountains), apparently identical with L. hi-Uncata, 

 Walk., from the British possessions. 



JErax, about five species, one of which (Twin Lakes) bears a decidedly 

 northern aspect; the others, on the contrary, seem to belong to the 

 fauna of the plains. 



Dasypogonina, several species; general character of the fauna of the 

 plains. 



Family Leptidje. 

 Atherix variegata, Walk., also found in the British possessions. 



Family Tabanidje. 



Contains no striking forms; the two or three species of the collection 

 all belong to the common type of the European T. tropicus, Lin., qua- 

 tuornotatus, Meig. Bromius, Lin., &c., which is represented by several 

 species in the northern portions of North America. Many descriptions 

 of these species exist, but, unfortunatel}', none of them precise enough 

 for identification. 



One of these Tabanus occured on the mountains, above the tree-line. 



Family Syrphid^. 



Yolucella, sp. (Colorado Plains); a single specimen. I have received 

 another specimen of this species from Mr. James Ridings in Philadel- 

 phia, who caught it in the same district. 



Yolucella, sp. (Twin Lake Creek) ; probably new ; type, northern ; 

 unfortunately a single imperfect specimen. 



Artophila sp. (Colorado Mountains) ; again a northern insect. 



