64 Papers from the Marine Biological Laboratory at Tortugas. 



between the posterior one and the ovary, somewhat variable in shape 

 but in the main subglobular; in some cases equal, in others the posterior 

 is the larger. Ovary near, in some cases, touching, the posterior testis; 

 in some cases larger, in others equal to, and in others smaller, than the 

 posterior testis, usually ellipsoidal with longer axis transverse to the long 

 axis of the body. Yolk-glands tubular, lying beside the ovary and ex- 

 tending a little way both in front and behind the ovary. In one case 

 there appeared to be only 2 of these tubular glands. In others there 

 were more, possibly as many as 4- The yolk-glands are much convo- 

 luted and consequently difficult to make out. The seminal vesicle, 

 testes, ovary, and yolk-glands are all ventrally situated. The folds of 

 the uterus for the most part lie dorsal to the other genitalia and behind 

 them, extending as far back as the base of the appendix. The metra- 

 term was not seen satisfactorily. It appears to lie dorsal to the base of 

 the cirrus-pouch, thence it was traced along the left side of the cirrus- 

 pouch to the base of the retracted cirrus. The excretory vessels do not 

 show distinctly in the mounted specimens, but it could be made out that 

 they end blindly lateral to the oral sucker. 



" Dimensions, life, flattened: Length 3; diameter 0.5; oral sucker 

 0.15; pharynx 0.08; ventral sucker 0.38; ova 0.017 by 0.008. 



Host, Clupanodon pseudohispanicus : July 10, 1906, numerous. 



Ectenurus sp., immature. (Fig. 155.) 



The specimens in this lot, which are small and immature, are near 

 Ectenurus (fig. 148). The following description is based on specimens 

 mounted in balsam: 



Body nearly linear; neck cylindrical, arched; neck and body crossed 

 by fine, transverse lines making a serrate outline; ventral sucker about 

 1.5 times oral. There is a slight projection of the head beyond the oral 

 sucker. There seems to be a very short esophagus and the intestinal 

 rami extend to the extreme posterior end. In one specimen the intes- 

 tines are convoluted in the tail region (fig. 155); in another they are 

 straight. Genital aperture ventral to the subglobular pharynx; cirrus- 

 pouch long, inclosing the seminal vesicle, the latter lying behind the 

 ventral sucker. Testes 2, close together and just behind the seminal 

 vesicle. 



Ovary a short distance behind the testes, oval; vitelline glands 

 tubular, beginning at the ovary and extending some distance back of it. 

 In two of the specimens the tail was inclosed in a sheath as shown in the 

 sketch (fig. 155). In the third specimen the tail was narrower than the 

 body and tapered uniformly to the posterior end. 



Dimensions of specimen figured: Length 2; breadth 0.28; length of 

 neck 0.35; oral sucker 0.16; pharynx 0.07; ventral sucker 0.25. 



Host, Auxis thazard: July 10, 1906, 1 fish, 3 distomes. 



Dinurus rubeus sp. nov. (Figs. 149-154.) 



This species resembles Dinurus longisinus Looss, but differs from 

 that species in having a preoral projection and in the character of the 

 seminal vesicle, which is without constrictions. 



