162 THE UNIVERSITY SCIENCE BULLETIN. 



sometimes be preserved by drawing glycerine under the cover 

 slip with filter paper. For toto counts, Mayer's haemalum gave 

 the best results. The sections were cut from five to seven micra 

 in thickness and stained with iron alum hsematoxylin. Good re- 

 sults were also obtained by staining with hsemalum and using 

 eosin or orange g. for counter stains. 



The free cercarias could be made to expand by heating slightly. 

 When they were in this condition the fixing fluid was poured on 

 suddenly, fixing the specimens in the best form for study. 



The measurements given in this paper were taken usually from 

 mounted specimens, and are not as accurate as those from living 

 forms would be, because of shrinkage of the specimens during the 

 process of fixing and mounting. 



Amphistome Cercari^. 



Three species of amphistome cercarise were found in my col- 

 lections. For the first of these I propose the name Cercaria cortii. 



Of twenty-three specimens of Planorbis trivolvis collected at 

 Cherryvale, Kan., October 16, one was infected with Cercaria 

 cortii. The snails were found adhering to rocks at a depth of 

 from six inches to a foot in a large pond of clear water. 



On October 17 the snails were isolated in individual watch 

 glasses and kept covered with water, the water being changed 

 each day. Cercarise were noticed in one dish as follows, the ob- 

 servations being made in the morning at eight o'clock: 



October 18 6 cercarise. 



October 19 12 cercariae; all others encysted. 



October 20 3 cercariae; all other cercarise encysted. 



October 21 cercarise; all other cercaria? encysted. 



October 22 cercarise; all other cercarias encysted. 



October 23 cercariae; all other cercarise encysted. 



October 24 cercariae; all other cercarise encysted. 



October 25 50 cercariae; five encysted. 



October 26 6 cercariae; all others encysted. 



November 2 All cysts still alive in water. 



November 3 One new cercaria encysted. 



November 4 One new cercaria encysting. 



November 6 One new cercaria; all encysted. 



November 5-7 No new developments. 



November 8 Snail dead. 



The cercarise within the cysts were alive after having been kept 

 in the water for twenty days, although only those that were opened 

 within four days after they encysted, moved about. 



