4 PROCEEDINGS OF THE NATIONAL MUSEUM vol.73 



The genital pore in the free form (fig. 1) has become indistinct 

 in the mounted specimen on account of the encroachment of anterior 

 folds of the uterus due to compression. 



Type.— C^it. No. 7915, U.S.N.M. ; paratype, Cat. No. 7916. 



PSILOSTOMUM LINEATUM, new species 



Figure 8 



Two distomes collected from the intestine of a herring gull {Larus 

 argentatus) at Woods Hole by Vinal N. Edwards, January 22, 1915, 

 are here considered. 



The longer of the two in formalin measured 5 mm. in length. In 

 balsam the lengths are 3.78 and 2.66, respectively. They are nearly 

 linear throughout with a breadth of about 0.5 mm. 



Neck short, evidently much shortened by contraction in these speci- 

 mens; ventral sucker much larger than oral; pharynx much smaller 

 than oral sucker and contiguous with it ; esophagus not plainly seen, 

 but apparently very short; intestinal rami extend to the posterior 

 end. The genital aperture was a little removed from the anterior 

 edge of the ventral sucker and slightly to the left of the median line. 

 In the specimen shown in Figure 8 the neck was somewhat distorted, 

 so that the genital pore is thrown farther from the median line than 

 it would be in an undistorted specimen. The cirrus-pouch is dorsal 

 to the ventral sucker, and has rather weak walls; seminal vesicle 

 relatively long, extending behind the ventral sucker. The two testes 

 are on the median line and separated from each other by a space a 

 little longer than the diameter of a testis. They are relatively large 

 and nearly circular in outline. The anterior testis is a little way back 

 of the middle of the length of the body. The ovary is about on the 

 median line and near the anterior edge of the first testis. It is some- 

 what pestle-shape, with an elongated anterior lobe, while the broader 

 posterior end is three lobed. There appears to be a seminal receptacle 

 near the anterior edge of the ovary. The uterus lies between the 

 ovary and the ventral sucker, the metraterm passing dorsal to the 

 ventral sucker. The vitellaria are very diffuse, filling the body back 

 of the testes, and extending in rather broad lateral bands as far 

 forward as the posterior margin of the ventral sucker in one of the 

 specimens, and to the level of the middle of the ventral sucker in the 

 other. A vitelline reservoir was visible immediately in front of the 

 ovary, and apparently ventral to the seminal receptacle. 



Dimensions of larger specimen in balsam: Length 3.78 mm.; 

 breadth 0.5; diameter of oral sucker 0.20; pharynx, length 0.14, 

 breadth 0.10; diameter of ventral sucker 0.32; ovary, length 0.28, 

 breadth of anterior lobe 0.10, at posterior end 0.15; first testis 

 length 0.38, breadth 0.30; second testis, length 0.46, breadth 0.38; 



