38 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



tion of S. nephropis. There are about 22 ventral suckers. The geni- 

 tal pore lies near the anterior border of the first ventral sucker, a 

 little to the right of the median line. The ovary is ventral and 

 lies just behind the fifth ventral sucker. The shell gland is at the 

 posterior median border of the ovary. The two testes are dorsal, 

 separated from each other by a distance less than the diameter of a 

 single testis and both lying between the sixth and seventh suckers. 

 The early folds of the uterus are filled with sperm and scattered 

 ova, A few follicles of the vitellaria were noted, lying along the 

 dorsal side, a little in front of the first testis; thence they extend 

 to within 1.5 mm. of the posterior end, as a single mass of more or 

 less pyriform follicles. Throughout the posterior half or more of 

 their course they occupy from one-third to one-half the diameter of 

 the body. The folds of the uterus are very voluminous, and fill most 

 of the body, from a point about 2.3 mm. from the anterior end to a 

 point about 4.3 mm. from the posterior end. The ova are very 

 numerous, oval-elliptical in outline, and have thick shells, about 0.1 

 by 0.06 mm. in the two principal diameters. None of the ova were 

 observed to have a lid at one end, as figured by Odhner. The intes- 

 tine and excretory vessels extend to very near the posterior end, 

 where the excretory vessels unite in a short muscular sinus. 



Measurements in balsam: Length, 42 mm.; breadth, 1 mm. from 

 the anterior end, 1.4 mm., maximum, about the middle, 1.75 mm.; 

 1 mm, from the posterior end 0.36 mm. ; pharynx, nearly circular in 

 outline, diameter, 0.28 mm.; ovary, length, 0.35 mm., breadth, 0.49 

 mm.; first testis, length, 0.63 mm,, breadth, 0.84 mm.; second testis, 

 length, 0.75 mm., breadth, 0.77 mm.; distance between testes, 0.35 

 mm. ; ova, 0.1 by 0.06 mm., thickness of shell, 0.01 mm. The ovary 

 is 0.21 mm. in front of the first testis, and about 14 mm. from thei 

 anterior end of the body. 



On August 2, 1926, Dr. Rudolph Bennett brought to my laboratory 

 several specimens of the immature stage of this trematode collected 

 from the rectum of a lobster {Homarus americarms) . These agree 

 with W. S. Nickerson's description of /S. nephropis from the Ameri- 

 can lobster.® The suckers range in diameter from 13 to 17 mm. 

 Rudiments on the testes, ovary, and vitellaria are present (U.S.N.M. 

 No. 8187). 



On May 23, 1930, Miss Carol Moore brought to my laboratory at 

 the University of Pennsylvania 15 specimens of the immature stage 

 of jS. nephropis^ which she had found encysted in the serous coat of 

 the rectum of a lobster. 



Zool. Jahrb., Abt. Anat. und Out., vol. 8, pp. 447-180, pis. 29-31, 1895. 



