COPULATION IN A TURBELLARIAN WORM. 303 



study of a single section this does seem to be the case, but 

 further examination shows the spermatozoa to be in a long skein, 

 much coiled, and surrounded by mucus. For a time at least the 

 uterus may function merely as a sperm receptacle. 



SUMMARY. 



1. Planaria maculata, and probably many other triclad 

 Turbellaria, mate with both copulants oriented in the same 

 manner. 



2. Impregnation is mutual, and simultaneous. 



3. During copulation the vasa deferentia are much distended 

 by their sperm contents, while the uterus may act temporarily as 

 a sperm receptacle only. 



