1908] BOA NE — NEW SPECIES OF TIPULA 49 



So far this species has been recorded as most abundant in the wind-swept hills 

 southwest of San Francisco where Mr. Williams says they occurred by the hundreds, 

 usually on the sides of the hills away from the ocean or in the lower places between 

 the hills. This would at first suggest that the winds might be a factor in this change 

 that is being brought about but the same species is also found further inland where 

 strong winds very rarely occur. As pointed out in the article on T. simplex we can 

 hardly see how natural selection can be the cause of such changes as this. Hetero- 

 genesis would more easily explain such cases. 



We propose, if possible, to study large series of these for a few years to see if 

 any appreciable change is actually taking place at the present time. 



