3io 



D. D. WHITNEY. 



spicuously present. The highest count for the motile sperma- 

 tozoa was about 200, while the highest count of the immotile 

 spindle-shaped spermatozoa was about 100. These counts 

 were made from males which were isolated at birth before they 



TABLE II. 



Hydatina senta. Showing the relative proportional number of the mature dimorphic 

 spermatozoa found in each testis. In general the large motile spermatozoa 

 were twice as numerous as the small spindle-shaped spermatozoa. 



had had an opportunity to pair with females and to shed their 

 spermatozoa. They show that the motile spermatozoa are 

 about twice as numerous as the immotile kind. Drawings and 

 counts of these two kinds of spermatozoa are shown in Fig. 3 



and Table III. 



TABLE III. 



Asplanchna amphora. Showing the relative proportional number of the mature 

 dimorphic spermatozoa found in each testis. In general the large motile sperma- 

 tozoa were twice as numerous as the small spindle-shaped spermatozoa. 



In addition to the spermatozoa of these three species of rotifers 

 already described the spermatozoa of six other species of rotifers 

 were carefully examined. These species were Polyarthra platyp- 

 tera, Diglena catellina, EucJilanis dilatata, Metopidia lepadella, 

 BracMonus urceolaris and Brachionus bakeri. In all cases the 



