RESEARCHES IN HELMINTHOLOGV AND PARASITOLOGY. Ill 



ance with its exterior position Cotylaspis possesses well-developed 

 eyes, while the imprisoned Aspidogaster is blind. It has occurred 

 to me that perhaps these two genera may represent two different 

 stages of existence of the same animal. 



Rlwpalocerca Tardigrada, Diesing. Attached to the mantle of 

 Anodonta fliiviatilis: specimens also obtained by Mr. L,ea from A . 

 laaistrii, . 



Heterosto)iiiL))i Ec/iiiiatitju, Filippi. From the oviduct of Paludina 

 decisa. Quite common. 



Cercaria Agilis, Leidy. Body, when elongated, narrowed pyri- 

 form ; when shortened, obcordate ; posteriorly emarginate ; ante- 

 riorly triangular. Mouth acetabuliform, large, globular. Acetab- 

 ulum little larger than the mouth, nearly central in the shortened 

 condition of the body, at the posterior third of the latter when 

 elongated. Sporocerca as long as the body, long clavate, trans- 

 versely plicated. Color white. 



Exceedingly active ; found in the Delaw^are river, quite commonlv 

 in company with Planorbis, Paludina, and Lymnea. 



Diplostomuni (iraudc, Diesing. Head oblong oval, a little oblique ; 

 margin entire, inflated. Mouth small, round. Male aperture small 

 round, female aperture large prominent, longitudinally oval. Body 

 conical. Ovaries dusky yellowish. Length i line ; breadth i-4th 

 line ; head 3-4ths line long ; bod}^ i-4th line long. 



Twenty specimens were obtained from the intestines of Stn'x 

 uivea. 



Monostountni Affiuc, lyeidy. Body spatulate, narrowest anteriorly, 

 flat ; posterior end obtuse with an excretory orifice communicating 

 with a well marked canal traceable as far forward as the commence- 

 ment of the oviduct. Mouth round, oral acetabulum small, followed 

 by a smaller pharyngeal bulb. Intestine simple, traceable on each 

 side to the posterior end of the bod}-. Testes four, posterior to the 

 position of the distended oviducts. Ovaries finely lobulated, situated 

 on each side external to the position of the intestine ; oviduct trans- 

 versely tortuous and distended with brown ova. Penis ensheathed, 

 long, tortuous, echinate. Generative aperture small, acetabuliform. 

 Ova oval and prolonged at one pole, or subopyriform. Length of 

 body 6^2 lines: breadth i line. 



Four specimens were obtained by Dr. J. M. Corse from the bile 

 ducts and gall-bladder of the muskrat {Fiber zibethicus) . Closely 

 allied to M /lippocrcpis, Diesing, but has no trace of the horseshoe- 

 like collar to the head. 



