321] NORTH AM ERIC AX POLYSTOMIDAE—STUXKARD 41 



Carolina. Goto (1899) in discussing the specimen described by Leidy 

 as P. oblongum, refers to the food terrapin as E. rugosa. 



Leidy gives no figure and his description states : "Polystomum coro- 



natum Body when elongate lanceolate. Caudal disc wider 



than the body, cordiform, with three pairs of bothria and with the body 

 attached between the anterior two pairs ; changeable in form to oblong, 

 circular or quadrate ; with three pairs of minute hooks between the 

 anterior part of bothria and with a larger pair and two smaller pairs 

 between the last pair of bothria. Genital aperture with a circular or 

 transverse oval coronet of thirty-two hooks of equal length. No eyes 

 visible. Length, elongated from 4 to 6 mm; contracting to about half 

 the length and widening proportionately." 



The specimen from which the present description was made (Fig. 

 27) is 3.15 mm. long and 0.83 mm. in width. The greatest width is at 

 the level of the vaginae ; the body tapers rapidly anteriorly, widening 

 again slightly at the anterior sucker. From the level of the vaginae 

 the body gradually grows narrower posteriorly to its insertion into the 

 caudal disc. The disc is 1.24 mm. wide at the level of the anterior 

 suckers, 1.2 mm. thru the middle pair and 0.78 mm. thru the caudal pair 

 of suckers. Each sucker is approximately 0.37 mm. in diameter, and 

 constructed as previously described. There are thirty-two small di- 

 visions in the peripheral cuticular band of the only sucker in which they 

 could be counted. The disc bears the usual eighteen hooks ; the six 

 larval booklets at the anterior margin of the disc are situated in a row 

 equidistant from the anterior edge of the disc, the two lateral hooks 

 on either side are nearer each other than the more centrally located one 

 is to the median one of that side. Larval hooklets are present in the 

 bases of the suckers and one pair is present between the caudal suckers. 

 Between the caudal suckers there are present also both a pair of great 

 hooks and a third pair intermediate in size between the two. The larval 

 hooklets are 0.02 mm. in length, the hooks of intermediate size are 0.051 

 mm., and the great hooks are 0.132 mm. 



The anterior sucker is oval, 0.16 mm. long and 0.4 mm. wide; the 

 pharynx is circular in outline, 0.3 mm. in diameter. No esophagus can 

 be seen in the toto preparation and behind the posterior margin of the 

 testis the ceca are obscured by the vitellaria. 



The testis is slightly anterior to the center of the body, circular in 

 outline, and 0.3 mm. in diameter. The vas deferens could not be distin- 

 guished ; the cirrus sac in ventral aspect is 0.19 mm. in diameter ; the 

 genital coronet contains thirty-two hooks, similar in size and shape, the 

 shanks being sickle-shaped. 



The ovary is situated on the right side of the body, about its own 



