[129] NOTES ON ENTOZOA OF MARINE FISHES. 847 



The larger of these two styles of hooks are, however, small- sized, and 

 correspond, both in shape and size, to the hooks in the inner series. The 

 smaller alternates of this row are but slightly recurved. The larger al- 

 ternates are about 0.0l7 mm long and 0.008 mm broad at base; the smaller 

 ones are 0.011 lnm long and 0.005 mm broad at base. To recapitulate, 

 there are four rows of large hooks on outer side of proboscis, four rows 

 of small hooks on inner side, two rows of intermediate hooks on each 

 side of the series of large hooks, one row of alternately larger and 

 smaller hooks on each side of the series of small hooks, thus making 

 fourteen rows in all. All the hooks are smaller and more slender near 

 the base of the proboscis. 



The fragment of strobile which was found associated with the scolex, 

 and which evidently belongs to it, does not contain any mature segments. 

 The posterior segments are somewhat elongated and are narrower than 

 the preceding segments. None of the genital organs could be made out 

 except the cirrus, which could be seen through the walls of the seg- 

 ment when the latter were rendered transparent with glycerine. The 

 male genital aperture is marginal about the middle. The walls of the 

 segments are traversed by many strong, longitudinal, muscular fibers. 



36. Rhyncliobothrium longicorne, sp. nov. 

 [Plate XIII, Figs. 4-8]. 



Head appressed, truncate, and emarginate in front. Bothria two, 

 lateral, oblong-elliptical, parallel in front, slightly divergent behind, 

 slightly emarginate on posterior edge, somewhat bilobed by a low, short, 

 longitudinal, median ridge near the posterior end of the shallow face. 

 Neck long, but capable of great contraction, subcylindrical. Pro- 

 boscides very long, three or four times as long as the bothria, tapering 

 to apex, with tumid basal portion covered with fine, slender, straighten 

 appressed hooklets ; remainder of proboscis armed with longer, slender, 

 curved hooklets of nearly uniform size. Proboscis-sheaths very long, 

 in contracted specimens lying in broad, crowded, sinuous folds. Con- 

 tractile bulbs elliptical or elliptical-oblong. Segments begin very soon 

 behind contractile bulbs ; at first very short, subsequently increasing 

 in length, then becoming as long as broad; last segments rectangular, 

 longer than broad. Body relatively short, compressed, at first a little 

 wider than neck and increasing in breadth but little throughout its 

 length. 



Genital apertures male marginal, near anterior edge, its position in 

 some specimens marked by an evident notch ; female lateral at middle 

 point of median line (?). Eggs oval about 0.04 mm in longer diameter. 



Habitat. — Odontaspis littoralis, spiral valve. Wood's Holl, Massa- 

 chusetts, July, 1885 ; August, 1886. 



I have found this species on two different occasions, each time in the 

 sand shark (Odontaspis littoralis). The first specimens, three in num- 

 ber, were collected July 15, 1885; the second, four in number, August 

 12, 1887. 



