126 PROCEEDINGS OF THE NATIONAL MUSEUM vol.88 



the serrations are faint, or have disappeared entirely. The oral 

 and ventral suckers are nearly equal and are separated from each 

 other by a space approximately equal to the diameter of one of them. 

 The diameter of the pharynx is about half that of the oral sucker. 

 Prepharynx and esophagus none, intestinal rami extend to end of 

 appendix. The genital pore is on the midventral line about half- 

 way between the oral and ventral suckers. The cirrus-pouch is 

 short, and the seminal vesicle is dorsal to the anterior border of the 

 ventral sucker. The two testes are close behind the ventral sucker, 

 near together, and slightly diagonal; they vary from circular to 

 oval-elliptical in outline. The ovary is situated toward the posterior 

 end of the body proper, and is usually oval-elliptical in outline, with 

 the longer diameter transverse. The vitellaria lie immediately be- 

 hind the ovary. They are lobed, and while there is considerable 

 variation in the lobation, the right one was usually three-lobed and 

 the left two-lobed. 



The seminal receptacle and shell gland lie behind the ovary be- 

 tween the vitellaria. The folds of the uterus are voluminous and 

 fill the body between the ventral Slacker and ovary; folds of the 

 uterus extend back of the ovary and vitelline glands but were not 

 observed to enter the appendix. Ova, in balsam, about 0.024 mm. by 

 0.012 mm. 



The above description is based on specimens from the eel. 



Hosts. — Sand launce {Ammodytes americanus) , American eel 

 {Anguilla rostrata)^ common herring {GUipea harengus)^ sea raven 

 {Hemitrifterus americanus^ ^ fishingfrog {Lophius piscatorius) , sil- 

 versides {Menidia notata)^ kingfish {M enticirrhus saxatllis)., silver 

 hake {Merluccius hiUnearis), tomcod {Microgadus tomcod), white 

 perch (Morone americana), American smelt {Osnierus mordax).^ pol- 

 lack {Pollachius mrens), hickory shad {Pomolobus mediocris), blue- 

 fish {Pomatomus saltatrix), remora {Remora remora), common 

 mackerel {Scomber scomhrus), codling {Urophycis chvss), codling 

 ( Urophycis tenuis ) . 



Record of collections. — From sand launce, one and fragment col- 

 lected July 5, 1912. Measurements, life: Length, appendix partly 

 retracted, 0.84 mm. ; breadth, 0.32 mm. ; diameter of oral sucker, 0.13 

 mm., pharynx, 0.05 mm., ventral sucker, 0.17 mm.; ova, 0.024 by 

 0.012 mm. In the fragment the diameter of the oral sucker was 

 0.14 mm., ventral sucker, 0.15 mm. 



One, collected October 29, 1913; length, 2 mm. in formalin. Six 

 (U.S.N.M. No. 8336), collected November 1, 1913; 2 to 4 mm. in 

 formalin, appendix everted. One, collected October 13, 1914 ; length 

 in formalin, appendix retracted, 1.73 mm., breadth 0.54 mm.; diam- 

 eter of oral sucker 0.22 mm., ventral sucker 0.23 mm., ova 0.028 by 



