1915.] NATURAL SCIENCES OF PHILADELPHIA. 501 



parallel vertical ridges (see Plate XX, fig. 72). Ninth sternite exten- 

 sive with a deep rounded emargination beneath, at the lateral end 

 of this emargination a subtriangular to rounded lobe with abundant 

 short pubescence; on either side of the middle line is a sharp chi- 

 tinized point, hidden or nearly so by the brush on the eighth sternite. 

 Penis-guard elongate, the sides subparallel, the ventral face at about 

 midlength with a sharp point on either side, this point directed 

 backward. Eighth sternite (see Plate XVII, fig. 29) with the 

 caudal margin truncated or very slightly concave, with a brush of 

 long yellow hairs on either side, these brushes connected by a few 

 scattered hairs in between. 



The female is similar to the male, but the antennae are short, the 

 four basal segments mainly yellowish, the remaining segments a 

 little darkened at the base, the apical segments uniformly dark 

 brown. Ovipositor with the tergal valves very short, stout, blunt 

 at the apex; sternal valves very short, high, obliquely truncated 

 (see Plate XXI, fig. 84). 



Habitat. — Northwestern United States. 



Holotype, cf, Beaver Creek, Montana; altitude 6,300 feet; August, 

 1913 (S. J. Hunter). 



Allotype, 9 , topotypic. 



Paratypes, 14 d^'s, 3 9 's, topotypic. 



The types are in the collection of the University of Kansas, para- 

 types in the collection of the author. 



The specific name is that of a Siouan tribe of Indians of the 

 Northwest. 



The only species with which this fly might be identified is Tipula 

 alta Doane (Annals of the Entomological Society of America, V, 44, 

 1912) from Wyoming. There are many discrepancies between the 

 descriptions of the two flies which lead me to believe that the present 

 form is a distinct insect; the head is not brown, but gray, with a 

 narrow brown median stripe; the lateral prsescutal stripes are 

 indistinct; the wings show a distinct vitreous spot beyond the stigma; 

 the size is larger and the cell 1st Mo is not open (this open cell 1st M^ 

 in alta is almost surely an abnormality of the type); the details 

 of the genitalia are not as described for alta — the ninth pleurite is 

 produced into a long spatulate point, the first appendage is an 

 elongate, cylindrical, fleshy lobe, not small and spatulate; the 

 inner appendage not at all as described for alia. 

 Tipula dietziana sp. n. 



Coloration grayish; praescutum dull yellow with three brown 



