1923 ] Probable Occurence of Parthenogenesis in Ochthiphila 23 
say that none was present. Yet several of these females con- 
tained what appeared to be fully formed eggs — in fact in a number 
of cases there was an egg already in the uterus. Such females, 
evidently laying eggs but without sperm present, were found as 
early as August 23 and as late as the middle of September. At 
both times there were also found females with ovaries still 
small — these again being without sperm. It seems clear thus 
that the results are not due to the collecting having been done 
either at the beginning of a generation, before males had emerged 
or at the end of one, after the males had mated and died. 
In addition to the live females just discussed, I have examin- 
ed the pinned material in my own collection, in the collection of 
the American Museum of Natural History, in that of the United 
States National Museum, and in that of Prof. J. M. Aldrich. 
All the specimens of 0. polystigma found in these collections 
were again females. The data thus obtained (including the live 
specimens examined) are summarized in Table I. 
Table I. Distribution of Ochthiphila poly stigma Meigen 
State or Province 
Number of females 
Months in which taken 
New Hampshire 
1 
? 
Ontario 
7 
May — 
Massachusetts 
89 
June — Sept 
Connecticut 
3 
May 
New YorU 
4 
Sept. 
New Jersey 
1 
Sept. 
Pennsylvania’ 
8 
Oct. 
Maryland 
3 
Apr. — Aug. 
Indiana 
10 
July — Aug. 
Illinois 
3 
June 
Wisconsin 
1 
July 
South Dakota 
1 
June 
Manitoba 
2 
July 
Utah 
2 
July 
Holland 
2 • 
June 
Total 
137 
Apr. — Oct. 
iTwo of the specimens from New York and all of those from Pennsylvania were taken by 
Dr. F. Schrader, and have not been seen by me. Dr. Schrader states that all were females. 
