126 proceedings of the academy of [1888. 



March 27. 



The President, Dr. Joseph Leidy, in the chair. 



Twenty-tive persons present. 



A paper entitled "Notes on the Myology of Ursus maritimiis," 

 hj Edw. A. Kelly, was presented for ^publication. 



Trematodes of the Mushrat: — Prof. Leidy stated that in the collec- 

 tion of the Academy there is a vial labelled "worms from the duo- 

 denum of the Muskrat." There are 25 worms, and in their present 

 condition they are pale brown bordered by dark brown, and measure 

 from 12 to 18 mm long by 1 to 1"5 mm broad. If -not identical, 

 they are closely allied to Distomum echinatuni, which in the mature 

 state lives in ducks and other water birds and in the larval state 

 in fresh water snails. The Muskrat eats the latter so that it may 

 likewise become infested in the same manner as the ducks and this 

 would also seem to make it probal)le that the parasite is the same. 

 Dujardin, Wedl, and others describe D. echinatuin as having the 

 fore-})art of the body echinate, which is not the case with the Distome 

 of the Muskrat, though in both the head is armed in the same 

 manner and with the same number of spines. Its characters are as 

 follow. 



Body long, flattened, baud-like, with the neck tapering and the 

 tail obtusely rounded. Head reniform, with a coronet of strong- 

 straight spines, from 30 to 36. Ventral acetabulum much larger than 

 the head, situated at the base of the neck a short distance behind 

 the latter, spherical. Body of nearly uniform width. Oral aceta- 

 bulum small; pharynx oval; intestines simple and narrow. Genital 

 orifice immediately in advance of the ventral acetabulum; cirrus 

 exsert to one side, curved and smooth ; testes situated almost mid- 

 way between the ventral acetabulum and tail; oviducts median be- 

 hind the ventral acetabulum ; ova oval, yellow; vitelline glands large 

 and conspicuous, racemose, extending along the intestines from the 

 ventral acetabulum to the end of the tail. 



Plead 0"5 to 0'6 broad; spines about 0"1 long by 0*02 thick; oral 

 acetabulum 0-25 ; pharynx O'o long, 0'225 wide; ventral acetabulum 

 0"875 to 1-25 mm. Ova 0*1 long by 0-072 broad. 



Since the above communication a collection of worms, from the 

 small intestine of a Muskrat, has been received. Eighteen of the 

 worms pertain to the supposed Distomum echlnatum, and range from 

 18 to 25 mm long. In all, the fore part of the body to a short dis- 

 tance behind the ventral acetabulum is finely echinate, while the 

 rest is smooth. Two other worms appear to belong to Amphlstoviuvi 

 siihtriquetrum., 12 and 15 mm long, a parasite previously observed 

 only in the Beaver of Europe. 



