o'roke: larval trematodes. 



177 



Percentage of Infected Snails 



Date. Pond. 



Host* 



Species. 



7- 7 

 7- 9 



7- 9 

 7-10 

 7-12 

 7-20 

 7-21 

 7-22 

 7-24 

 7-31 

 7-31 

 7-31 



8- 2 

 8- 3 

 8- 4 

 8- 4 

 8-18 

 8-18 

 8-19 

 8-20 

 8-28 

 8-28 

 8-28 

 8-28 

 8-28 

 8-29 

 8-29 



8-30 

 8-31 



8-31 

 10- 7 

 10- 7 



10- 8 

 10-12 

 10-19 

 10-19 

 10-19 

 10-19 

 10-19 

 10-19 ' 

 10-19 

 10-19 

 10-20 

 10-21 I 



11- 9 

 11- 9 i 

 11- 9 



9 

 10 

 11 



1 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 17 



16 

 17 



16 



12 

 5 

 19 

 19 

 21 

 22 

 23 

 25 

 26 

 27 

 28 

 29 

 30 

 30 

 31 

 32 

 33 



Physa gyrina 



1 Physa gyrina 



I Physa gyrina 



I Physa gyrina 



I Physa gyrina 



Physa gyrina 



Physa gyrina 



I Physa gyrina 



I Physa gyrina 



j Planorhis irirolris . 



Physa gyrina 



Physa gyrina 



I Physa gyrina 



I Physa gyrina 



Physa gyrina 



Physa gyrina 



I Physa gyrina 



I Physa gyrina 



1 Physa gyrina 



, Physa gyrina 



; Physa gyrina 



Planorbis tritolris. 



Planorbis Irirolris. 



Planorhis trirolris . 



Planorbis trirolris. 



Planorbis trirolris. 



Planorbis trirolris. 



Planorbis trirolris . 



Planorbis trirolris. 

 Planorbis trirolris . 



Planorbis trirolris . 



Physa gyrina 



Planorbis trirolris . 



Planorbis irirohis. 



Planorbis trirolris . 



j Physa gyrina 



I Physa gyrina 



Physa gyrina 



' Physa gyrina 



! Physa gyrina 



; Physa gyrina 



j Physa Integra 



• Physa gyrina 



i Physa gyrina 



Physa gyrina 



' Physa gyrina 



Ph ysa gyrina 



Physa ovrina 



25 

 20 

 95 

 50 

 20 

 33 

 130 

 23 

 30 

 15 

 6 



10 

 12 

 20 

 10 

 10 

 12 

 100 

 100 

 16 

 30 

 20 

 20 

 20 

 29 

 25 



50 

 50 



2 



1 















6 











1 



1 















1 



2 



















1 



6 



4 



13 



3 



16 



16 



13 



21 



2^ 



45 



34 



2 



C. ineersa. 

 C. haskelii. 



C. inrersa. 



C. inrersa. 



C. magnacauda. 



C. inrersa. 

 C. inrersa. 



C. fust for mis. 

 C. eehinorauda. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansieTisis. 

 C. kansiensis. 

 C. kansiensis. 

 C. kansiensis. 

 C. inrersa. 

 C. kansiensis. 

 C. kansiensis. 

 C. inhabilis. 

 C. kansiensis. 

 C. echinocauda. 

 C. inhabilis. 

 C. inhabilis. 

 C. inhabilis. 



C. haskelii. 

 C. haskelii. 

 C. haskelii. 



C. gracilis. 



C. gregaria. 

 C. cortii. 



Favorable circumstances enabled the writer to continue his in- 

 vestigations of the cercarice described in this paper during the 

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

 \icinities of Lawi'ence and Pratt were resurv^eyed, 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 

 gi'oups, one consisting of an infection of Cercaria inrersa in rediae 

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



12— Sci. Bui. X. 



