850 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [132] 



37. Otobothrium crenacolle, sp. nov. 

 [Plate xin, Figs. 9-15, and Plate xiv, Figs. 1-4. ] 



Head broad, transverse, hammer- shaped, or, in alcoholic specimens, 

 bluntly rounded in front and cordate, compressed. Bothria two, oppo- 

 site, lateral, sub-rectangular or oblong-elliptical, bilocular, slightly 

 emargiuate on posterior edge, converging in front, widely divergent 

 behind ; each bothrium with two eversible, ciliated pits at the posterior 

 edge. Faces of bothria hollowed out, edges somewhat thickened. 

 Neck short, cylindrical, slightly compressed, broader, and much thicker 

 than anterior part of the body, from which it is quite distinct, posteri- 

 orly projecting into a kind of collar with four deep notches opposite the 

 sides and margins of the body. Proboscides slender, about twice the 

 length of a bothrium, armed, for the most part, with strongly recurved 

 hooklets, which are sharp-pointed with broad bases of uniform size and 

 symmetrically disposed ; about five visible at once in each of the diag- 

 onal rows. There are beside these some minute slender hooklets near 

 the base of the proboscides. The proboscis-sheaths are spiral. The 

 contractile bulbs are short, oval, and lodged at the base of the neck in 

 the projecting lobes made by the posterior notches of the neck. The 

 body is slender, compressed, and much narrower at first than the neck. 

 First four segments very short, three or four times as broad as long. 

 The remaining segments increase in length, rapidly becoming very long 

 and slender, the posterior segment often from twelve to fifteen times as 

 long as broad. Free proglottides slender, somewhat irregular in out-- 

 line, very active. Ova subglobular, .abundant. Genital apertures, at 

 least male, marginal a little behind middle point. 



Habitat. Kphyrna zygwna, spiral valve, July 28, 1886, one hundred 

 and fifty specimens; July 18, 1887, one hundred specimens; chyle 

 swarming with free proglottides on both occasions. Wood's Holl, 

 Massachusetts. 



Numbers 1 and 2 of the following are from living specimens ; 3 and 4, 

 alcoholic. 



