208 Marsh—Limnetic Crustacea of Green Lake. 
With the exception of three individuals in the collection of 
March 27, 1895, I found no Leptodora from the latter part of 
October to the middle of June. It was present pretty generally 
in the summer collections, but never in very large numbers. 
The largest number that I obtained in any collection was 
twenty-four. 
In its vertical distribution, Leptodora is commonly within ten 
meters of the surface. I have found individuals at a depth of 
between twenty-five and thirty meters, but it is not a common 
occurrence. 
Leptodora was never present in sufficient numbers in my col¬ 
lections so that I could draw any inferences in regard to the 
effect changes of temperature would have on its vertical distri¬ 
bution. 
It will be noticed that my observations in regard to the sea¬ 
sonal distribution of Leptodora correspond very closely with 
what Zacharias says of Leptodora in Ploener See, for he states 
that it disappears in the course of the month of October, and 
appears again towards the end of May. (Zacharias, ’94, p. 100. 
Also, Apstein ’96, p. 175. Fri§ and Vavra, ’94, pp. 55, 108.) 
Apstein (’96, p. 80) states that Leptodora is found most abun¬ 
dantly in the deep water. This is certainly not according to my 
observations, as they would indicate that it should rather be 
considered a surface form, although it is by no means confined 
to the immediate surface. As Apstein does not state what he 
means by deep water in this case, the seeming contradiction in 
our observations may be more apparent than real. 
