48 PSYCHE [June 



Alameda Co., Cal., with abortive wings which are hardly twice as long as the hal teres; 

 in all the other characters, as well as in the structure of the hypopygium, they agree 

 with the males of T. prcecisa. I suppose this is a case of dimorphism. " He then 

 mentions this species as having been taken at the same time and place as the apterous 

 Bitticus which is rather common at times. 



For a long time we have had in our collections here at Stanford a poorly preserved 

 sub-apterous female Tipula which I have been unable to identify. Indeed I thought 

 it might be one of the common species that had failed to expand its wings after 

 issuing from the pupa. Last winter however Mr. Williams found these sub-apterous 

 forms very common in and about San Francisco and the three pairs that he brought 

 in show that they cannot be placed with T. prcecisa, which they, at first sight, closely 



resemble except for the short wings. They differ from 

 prcecisa in several respects, the most important of which 

 are in the structure of the hypopygia and the ovipositors. 

 In pr&cisa, which is one of our most common California 

 forms, the posterior margin of the eighth sternite of the 



Wings of Tipula vestigipennis , , , , , . . . i • 1 • i 1 1 



male has a very deep rounded incision which is bordered, 

 broadly toward the apex, narrowly on the sides, by a lighter colored membrane 

 from the middle of which arise two parallel tufts of long reddish hairs. In vestigi- 

 pennis this sternite is only gently excised medianly, the whitish membrane almost 

 or quite filling the incision. The two tufts of whitish hairs which arise from this 

 membrane instead of extending parallel cross each other close to the base at an angle 

 of about forty-five degrees. The posterior margin of the ninth tergite of the male of 

 prwcisa has a very deep broad V-shaped incision which almost or quite divides the 

 tergite. In vestigipennis the posterior margin of this tergite is gently rounded with 

 a median pair of brownish triangular processes. There are other differences in the 

 hypopygia but these are the most striking and easily detected. The most noticeable 

 difference in the ovipositors of the two species is in the shape of the tip of the upper 

 lamella. In prcecisa they are obliquely truncated and slightly excised. In vestigi- 

 pennis they are drawn out to a very sharp point. 



So we have here not a case of dimorphism as Osten-Sacken suspected, but 

 another species of this family Tipulidse, which is so abundantly represented in Cali- 

 fornia, in which the wings are apparently becoming vestigial. The fact that there 

 is so great a variation in the degree of development in the few specimens before me 

 would indicate, it seems, that this tendency or condition is only a recently acquired 

 one for although they can no longer serve as organs of flight they have by no means 

 reached the stage of degeneration that is represented by the females of Tipula sim- 

 plex Doane. (Ento. News, Vol. 18, No. 1.) 



