18 ILLIXOIS BIOLOGICAL MONOGRAPHS [298 



P. ocellatum Rudolphi 1819. From the throat and nasal cavity of 

 Emys europa and Halichelys atra; Europe. 



P. ohlongum Wright 1879. From the urinary bladder of Aromo- 

 chclys odoratus; North America. 



P. coronatum Leidy 1888. From the fauces of the terrapin ; North 

 America. 



P. hassalli Goto 1899. From the urinary bladder of Cinosternum 

 pennsylvanicum, Aromochclys odoratus, A. carinatus, and Chelydra ser- 

 pentina; North America. 



P. bullicnsc Johnston 1912. From the urinary bladder of Hyla 

 phyllochros and H. Lcsueurii; Australia. 



P. alluaudi, Beauchamp 1913. From an unknown batrachian ; 

 Africa. 



P. kachugae Stewart 1914. From the urinary bladder of Kachuga 

 lineata; India. 



In the present work evidence is submitted to justify the inclusion of 

 the following new species: 



P. orhiculare Stunkard 1916. From the urinary bladder of Pseu- 

 demys scripta and Chrysemys marginata; North America. 



P. opacum Stunkard 1916. From the pharynx of Trionyx fcrox and 

 Malacoclemmys lesueurii; North America. 



P. mcgacotyle Stunkard 1916. From the mouth of Chrysemys mar- 

 ginata; North America. 



P. microcotyle Stunkard 1916. From the mouth of Chrysemys mar- 

 ginata; North America. 



With the exception of P. integerrimum, the members of the genus are 

 very rarely found and the number of individuals discovered is very small. 

 Wright described P. ohlongum from two specimens; Leidy, P. corona- 

 tum. from four specimens; Johnston had sixteen specimens of P. iulliense; 

 Beauchamp described P. alluaudi from a single specimen ; Stewart had 

 only two specimens of P. kachugae. The writer had only a limited num- 

 ber of individuals of any species ; P. microcotyle was described from a 

 single specimen; P. orbicidare from nine specimens; P. opacum and P. 

 megacotyle each from three specimens. Becavise of the limited amount 

 of material, it has been impossible to attempt special technique to differ- 

 entiate the various organ systems, and the descriptions are therefore in- 

 complete in certain particulars. The general morphological features are 

 however described in sufficient detail that clear specific diagnoses can be 

 made, and in certain instances the finer structure and histology of the 

 organs has been described. 



