[Ill] NOTES ON ENTOZOA OF MARINE FISHES. 829 



The sketch made from a living proglottis, Fig. 8, Plate X, shows the 

 character of the cirru s bulb, the vagina, and some of the convolutions of 

 the vas deferens. The vagina expands to form a large receptaculum 

 seminis. This feature was indicated in sectious of preserved specimens 

 by the relaxed and folded walls of the vagina. In the figure the ovaries 

 are obscured by the large, globular, spermatic capsules of the testes. The 

 cirrus bulb is oblong, its inner end directed forward. It frequently 

 protrudes in a broad, expauded collar a short distance beyond the mar- 

 gin of the segment. The cirrus is smooth. It is shown ill Fig. 9 with 

 spermatozoa issuing from its extremity. The spermatozoa are ejected 

 in large quantities and appear to be felted together in elongated masses 

 without any fluid medium. 



28. Rhynchobothrium tumidulum y sp. nov. 

 [Plate xi, Figs. 3-11.] 



Head with two round-oval or elliptical bothria, which are marginal or, 

 by torsion, lateral, approximate anteriorly, widely separated poste- 

 riorly, emarginate on posterior border in life, almost entire in alcoholic 

 specimens, very mobile. Neck variable in length according to state of 

 contraction, but comparatively long — that is, three to five times the 

 length of the head ; in life subcylindrical,very elastic, capable of being 

 much elongated or greatly shortened, and with a crimson spot in front 

 of contractile bulbs. Proboscides long, slender, longer than the bothria, 

 slightly enlarged at base; armed with minute hooklets of two kinds, 

 one short, sharply and abruptly recurved with a broad base, the other 

 slender, a little longer than the first kind, arcuate. Hooklets on tumid 

 base short, and crowded in close spirals. Proboscis sheaths spiral, con- 

 tractile bulbs long, slender, arcuate, sometimes decussate. Body con- 

 tinuous with neck, the first segments faintly outlined by transverse 

 striae. The first distinct segments appear at a short distance behind 

 the contractile bulbs and are much broader than long ; succeeding seg- 

 ments squarish, sometimes with rounded corners, soon becoming longer 

 than broad ; posterior segments several, five or more times as long as 

 broad, often fusiform, sometimes with deep emargination at posterior 

 end, separating easily from strobile. Whole number of segments twelve, 

 more or less. Male genital aperture marginal, near posterior third. 

 Length, 5 to 12 mm . 



Habitat. — Mustelus canis, spiral valve, frequent, Wood's Holl, Massa- 

 chusetts, July and August. 



I have obtained this species from the spiral valve of the smooth dog- 

 fish (Mustelus canis) on several different occasions, but never in great 

 numbers. It is usually associated with R. bulbifer, Galliobothrium verti- 

 cillatum, and C. eschrichtii. 



