280 DIPTERA FROM SOUTHWESTERN UNITED STATES 



and general chaetotaxy, with the exception of the mid femora and 

 the form of the apex of the hind tibiae, which were overlooked by 

 Aldrich. The distinctions of value in separating the species are 

 listed in the keys on a preceding page and are constant throughout 

 a long series of specimens. 



I have refused to recognize the specific name aienima as ap- 

 plicable to any of the species before me, because I do not know 

 to which of the three it may be applied, if it can be appHed to 

 any. These mountain forms are not very widely distributed as 

 a general rule and I prefer to consider the species all distinct 

 from aterrima, which was described from Mexico, until the type 

 specimen of that species can be more fully described. 



Similis is rather larger than minor, equalling aldrichi in size, 

 but is not so robust as the latter. The mid femora in the male 

 is more robust than in either of these species and is not ap- 

 preciably curved, and in addition to the difference in chaetotaxy 

 of this pair of legs the apex of the hind tibia is transverse, without 

 a slight but distinct protuberance on ventral surface. 



The females of all three species are very similar but may be 

 separated by the characters cited in the key. Length, 4.5 to 5.5 

 mm. 



Type. — cf ; Beulah, New Mexico, top of range, June 28, 1902, 

 [A. N. S. No. 6200]. Paratypes.—Q o", 5 9, topotypical; 19, 

 Claremont, California, [Illinois]; 1 cf , Tennessee Pass, Colorado, 

 July 25, 1917, (Aldrich), [Illinois]; 1 d', John Smith Ranch, 

 Colorado, July 3, 1913, [U. S. Biol. Surv.]; Bozeman, Montana, 

 June 20, 1906; 3 d', 1 9 , same locality, July 3, 1902; 1 9 , same 

 locality, July 7, 1902; 1 9 , same locality, May 30, 1916, [all 

 Montana Exp. Sta.] ; 1 9 , Gallatin Mountains, Montana, 6000 

 feet alt., June 1, 1914, [Montana Exp. Sta.]. 



I have before me one male and two females taken in Newfound- 

 land, which either belong to this species or to one very closely 

 allied to it. 



Pogonomyia xninor sp. n. 



This species averages smaller (3.5 to 4.5 mm.) than the other 

 two and appears to be the commonest Colorado and New Mexico 

 form. 



For characters see notes and keys under previous species. 



