4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 8i : abt. 6 



terior testis. According to the measurements given by Braun 

 (1900b), in TJ. sedbrtdwtn the distance between the oral sucker and 

 the acetabulum is more than three times the corresponding distance 

 in U. lasmrensis. The diameter of the ovary of U. scdbridum, as 

 figured by Braun (1900b), is about the same as that of the acetabu- 

 lum, while in U. lasiurensis the diameter of the ovary is considerably 

 larger than that of the acetabulum. The oral and ventral suckei-s 

 are also considerablv smaller in U. lasiurensis than those in U. 

 scahridv/m. 



V. lasiurensis may be differentiated from U. shillingeri on the 

 basis of the body size and the extent of the vitellaria. U. shillingeri 

 is much smaller than the species discussed in this paper, and its 

 vitellaria extend from the level of the anterior margin of the acetab- 

 ulum to a short distance caudad of the ovary. 



Comparisons of the more important characters of the species of 

 Urotrema are given in Table 1. 



REFERENCES 



Braun, Max. 



1900a. Einige Bemerkungen iiber die Fascioliden der Chiroptera. Zool. 



Anz., vol. 23, pp. 387-391. 

 1900b, Trematoden der Chiroptera. Ann. Naturh. Hofmuseums Wien, vol. 15, 

 pp. 217-236, pi. 10, figs. 1-13. 

 Peice, E. W, 



1931. Four new species of trematode worms from the muskrat, Ondatra 

 zibethica, with a key to the trematode parasites of the muskrat. 

 Proe. U. S. Nat. Mus., vol. 79, art, 4, pp. 1-13, figs. 1-A. 



V. S. ceVERHHEaT PRIRTlie OFFICI: Itt2 



