o'roke: larval trematodes. 



177 



Percentage of Infected Snails. 



Host. 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Planorbis trivolvis. 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Planorbis trivolvis. 

 Planorbis trivolvis. 

 Planorbis trivolvis . 

 Planorbis trivolvis. 

 Planorbis trivolvis . 

 Planorbis trivolvis . 

 Planorbis trivolvis . 



Planorbis trivolvis. 

 Planorbis trivolvis. 



Planorbis trivolvis. 



Physa gyrina 



Planorbis trivolvis. 

 Planorbis trivolvis. 

 Planorbis trivolvis. 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa inlegra 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Physa gyrina 



Number 



of 



snails. 



25 



20 



95 



50 



20 



33 



130 



23 



30 



15 



6 



5 



5 



10 



12 



20 



10 



10 



12 



100 



100 



16 



30 



20 



20 



20 



29 



25 



50 

 50 



90 

 50 

 13 

 12 

 23 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 50 

 27 

 50 

 100 

 25 



Number 

 infected. 



2 

 1 

 

 

 

 6 

 

 

 1 

 1 

 

 

 

 1 

 2 

 

 

 

 

 1 

 6 

 4 

 13 

 3 

 16 

 16 

 13 

 21 

 2 

 45 

 34 

 2 

 75 

 1 

 2 

 2 

 1 

 

 2 

 

 2 

 

 

 2 





 7 

 5 

 

 

 



Species. 



C. inversa. 

 C. haskelli. 



C. inversa. 



C. inversa. 



C. magnacauda. 



C. inversa. 

 C. inversa. 



C. fusiformis, 

 C. echinocauda. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. inversa. 

 C. kansiensis. 

 C. kansiensis. 

 C. inhabilis. 

 C. kansiensis. 

 C. echinocauda. 

 C. inhabilis. 

 C. inhabilis. 

 C. inhabilis. 



C. haskelli. 

 C. haskelli. 

 C. haskelli. 



C. gracilis. 



C. gregaria. 

 C. cortii. 



Favorable circumstances enabled the writer to continue his in- 

 vestigations of the cercariae described in this paper during the 

 summer and fall of 1916, and as late as January 5, 1917. The 

 vicinities of Lawrence and Pratt were resurveyed, with the results 

 that the species found the preceding year were verified by re- 

 peated collections and comparisons. Cercaria magnacauda was 

 not found this season. 



Many cases of double infection were found in Physa gyrina from 

 pond No. 1. These cases of double infection were confined to two 

 groups, one consisting of an infection of Cercaria inversa in rediae 

 in the digestive gland, and unidentified cysts in the body cavity, 



12— Sci. Bui. X. 



