120 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.83 



the ventral sucker is about twice that of the orah The diameter of 

 the pharynx is about half that of the oral sucker. There is no esoph- 

 agus, and the intestinal rami extend to the posterior end of the 

 appendix. The genital pore is at the posterior margin of the oral 

 sucker. The seminal vesicle is behind the ventral sucker and in front 

 of the testes, which are near together and diagonally placed. The 

 ovary and vitellaria are situated toward the posterior end of the body 

 and are separated from the testes by folds of the uterus. The ovary 

 is more or less oval in outline, the longer diameter transverse. The 

 two vitellaria lie at the posterior margin of the ovary, and, so far as 

 observed in material from the herring, they ai)pear to be but little 

 lobed. The folds of the uterus were observed to enter the appendix 

 for a short distance. The ova measure about 0.024 by 0.014 mm. in 

 the two principal diameters. In balsam mounts the ova are usually 

 collapsed and much crowded together. 



Hosts. — Filefish {Ceratacaiithus schoef-fi)^ menhaden {Brevoortia 

 tyr annus) ^ common herring {Glwpea harengus), round herring {Etim- 

 meus sadina), common eastern stickleback {Gladiunculus bispinosios) , 

 rudderfish {Palinurichthys percifoi'tnis) , summer flounder {Para- 

 lichthys dentatus), pollack {Pollachias vire7is), glut herring {Pomo- 

 lobus aestwalis), hickory shad {Pomolohus mediocris), alewife {Po- 

 molohus pseudo harengus) ,vfintev flounder {Pseudopleuronectes amer- 

 icanus), common mackerel [Scomber scombrus), rudderfish {Seriola 

 zonata), connnon scup {Stendtomus chrysops), striped anchovy {An- 

 choviella epsetus)^ lizardfish {Synodus foetens), cunner {Tautogola- 

 bms adspersus), codling {Urophycis tenuis). 



Record of collections. — From fileflsh : One, collected August 7, 1905. 

 Measurements in balsam: Length, 1,54 mm.; breadth, 0.35 mm.; 

 diameter oral sucker, 0.06 mm., pharynx, 0.04 mm., ventral sucker, 

 0.15 mm. ; ova, 0.021 by 0.012 mm. 



From menhaden: One, collected August 26, 1903; immature, very 

 active, length varying from 0.6 to 1.2 mm. ; excretory vessel filled with 

 spherical bodies; seminal vesicle filled with sperm. One, collected 

 July 11, 1905; measurements in balsam: Length 1.18 mm., breadth 

 0.19 mm. ; length of appendix, 0.45 mm. ; diameter of oral sucker 0.00 

 mm., pharynx 0.04 mm., ventral sucker 0.11 mm. ; ova about 0.024 by 

 0.012 mm. 



From common herring: Two, collected xlugust 14, 1905; length 

 0.8 mm. ; ova 0.024 by 0.012 mm. One hundred and fifteen distomes 

 (U.S.N.M. No. 8319) collected July 1 to August 29, 1919, from 20 

 small fish, measuring from 40 to 85 mm. in length; smallest number 

 in one fish one, largest number in one fish 20; some adult with ova. 

 Three, collected July 17, 1920, from a 75-mm. fish. One, collected 

 July 17, 1920, from a 75-nmi. fish. Two, collected August 17, from a 

 60-mm. fish. 



