Worm Parasites 71 



tion and a tail-like hinder part and measures .49 mm. in length and 

 .41 mm. in width, in the widest place. 



Lyninaea palustris (O. F. Miiller). Ten snails were examined, 

 of which the livers of six were infested with minute gymnocephalous 

 cercariae. The snails which were not infested were all of small size. 

 In all of these snails one or two oligochaetous Annelids belonging 

 to the genus Chaetogaster were found in the mantle cavity. 



Lyninaea stagnalis lilliana Baker. Eighteen snails were examined, 

 of which ten contained each one or two Annelids of the genus Chaeto- 

 gaster. No other worms were found. 



Physa luarreniana Lea. Thirteen snails were examined, the 

 livers of five of which contained numerous rediae and gymnoce- 

 phalous cercariae. The rediae have a length of i mm. The cercariae 

 are about .5 mm. long and have a long slender tail which is about 

 twice the length of the body. Six of the snails had each one or two 

 Annelids of the genus Chaetogaster in the mantle cavity, 



Planorhis antrosus Conrad. Thirteen snails were examined, 

 the livers of two of which were heavily infected with sporocysts and 

 xiphidiocercariae. One snail had a Chaetogaster in the mantle 

 cavity. 



Planorhis companulatus Say. Twenty-five snails were examined, 

 of which the livers of six contained numerous sporocysts of undeter- 

 mined affinities. One or two Chaetog (Asters were taken from each of 

 three snails. ' 



Planorhis trivolvis Say. Nine snails were examined and no 

 internal parasites found. Three snails contained Chaetogasters in the 

 mantle cavity. 



