138 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



the testes to a point a little in advance of the middle of the posterior 

 testis. The two testes are placed a little diagonally a short distance 

 behind the ventral sucker, round to subtriangular in outline, the 

 right testis a little in advance of the left. The ovary lies behind 

 the testes, is oval-elliptical in outline, its longer diameter transverse. 

 At its posterior border is the seminal receptacle, which is usually 

 spacious. The shell gland is situated behind the left ventral border 

 of the ovary to the left of the seminal receptacle. The vitellaria 

 tubular. There appear to be about three on each side. Anteriorly 

 they extend to about the level of the left testis and the posterior 

 border of the right testis, posteriorly they extend some distance back 

 of the ovary. The folds of the uterus in adult individuals are 

 voluminous, filling the dorsal region of the body from the ovary to 

 the ventral sucker, and behind the ovary to the appendix into which 

 they may press for a short distance. The accumulated ova may 

 crowd the testes forward to the level of the ventral sucker. The 

 excretory vessels are lateral from the ovary to the dorsal side of the 

 pharynx, where they unite. The lateral vessels at their posterior 

 ends unite on the dorsal side of the ovary and continue as a single 

 vessel to the posterior end. 



Measurements of a specimen from Menidia notata^ in balsam: 

 Length, 5 mm. ; breadth at level of oral sucker, 0.35 mm,, at ventral 

 sucker, 0.80 mm. ; maximum breadth, at about middle of length, 1.40 

 mm., near posterior end, 0.35 mm. ; diameter of oral sucker, 0.21 mm., 

 of pharynx, 0.14 mm., of ventral sucker, 0.46 mm.; right testis, 

 length, 0.44 mm., breadth, 0.44 mm.; left testis, length, 0.52 mm., 

 breadth, 0.39 mm.; ovary, length, 0.35 mm., breadth, 0.52 mm.; ova, 

 about 0.018 by 0.012 mm. 



Hosts. — American eel {Anguilla 7'ostrata)^ squeteague {Cynoscion 

 regalis)^ sea raven {Hemitripterus americanus), silver hake {Merlv£- 

 ciits hilinearis), silversides {Menidia notata), kingfish {Menticirrhus 

 saxatilis), toadfish {Opsanus tau)^ summer flounder {ParaUchthys 

 dentatus), common gurnard {Merulinus caroliniis), northern barra- 

 cuda (Sphyraena borealis), lizardfish (Synodtts foetens). 



Record of collections. — From American eel : One, collected August 

 30, 1910; length, 7 mm.; breadth, 2 mm.; fusiform. One (U.S.N.M. 

 No. 8366), collected November 7, 1911; length, in formalin, 6 mm. 

 Four, collected November 21, 1912 ; 2.5 to 6.5 mm. 



Some of the following notes were made on a collection of nine 

 distomes, measuring from 5 to 10 mm. in formalin, from the stomach 

 of an eel taken in Chesapeake Bay, October 31, 1921. 



The body in general is fusiform, although presenting a variety of 

 shapes due to different degrees of contraction. Sagittal sections show 



