184 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Female : Length 10 mm. ; wing 5.4 mm. 



Rostrum, palpi and antennae black. Head black. 



Pronotal scutellum obscure yellow. Mesonotum black. 

 Pleura black, the dorso-pleural membrane obscure yellow. Hal- 

 teres brown, the knobs darker. Legs black, short and stout ; 

 fore and hind tarsi shorter than their respective tibiae. Wings 

 semiatrophied, tinged with brown ; stigma dark brown ; veins 

 dark brown. Venation: Rs elongate, about equal to R 1+2 ; de- 

 flection of R 4+5 obliterated or very short; but two branches issue 

 from cell ist M 2 ; m-cu connecting with M at or before the fork. 



Abdomen black, the caudal margins of the segments very 

 narrowly ringed with yellow. Ovipositor with the tergal valves 

 greatly exceeding the relatively short sternal valves. 



Holotype, female, No. 820, Mus. Calif. Acad. Sci.; collected 

 by G. Dallas Hanna, June 30, 1920. One female paratype was 

 collected at the same time. 



Type locality, St. George Island, Alaska. 



Tipula pribilovia is a remarkably anomalous insect in many 

 respects. Although the wings are semi-atrophied, distorting the 

 venation to some extent, there is no doubt that only two branches 

 of media attain the wing-margin. There are but three genera 

 of Tipulinae known in which this latter condition obtains and 

 these are antipodal in their distribution. The discovery of the 

 male sex of this fly will be of great interest. The elongate 

 sector is a character of the genus Tipula, but the situation of 

 m-cu at or before the fork of M is almost as decisively a character 

 of Nephrotoma. 



