794 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [76] 



eter. A little farther back they are oval, and measure .02 mm and .01 mm 

 along the two diameters.* 



This species is evidently near Van Beneden's Phyllobothrium auricula 

 (Mem. Vers. Iutest., 124, Plate xvi, 6-12), fromTrygon pastinaca. 



Ant hoceph alum, gen. nov. 



Body articulate tsenireform; head separated from body by neck; 

 bothria four, unarmed, cruciforinly disposed, mounted on very versatile 

 pedicels, which contract in alcoholic specimens so as to appear sessile. 

 Borders of bothria very flexible, crenulate, with a single supplemental 

 disc on anterior edge; face smooth, no inyzorhynchus ; genital apertures 

 marginal. 



The alcoholic specimens suggest the genus Phyllobothrium. The dis- 

 tinctly pediceled bothria, however, which were quite evident in the 

 living specimens, exclude them from that genus. The crenulate border 

 of the bothria, which is caused by a row of small loculi, the long neck 

 and the slender, versatile pedicels exclude them from the genus Crosso- 

 bothrium. The immature segments of the strobile bear a strong resem- 

 blance to those of Spongiobothrium variabile. 



1G. Antliocephalum gracile, sp. nov. 

 [Plate vn, Figs. 1 and 2.] 



Head in the living worm with four leaf-like, opposite bothria, mounted 

 on very flexible pedicels. Each bothrium with a single supplemental 

 disk on the inner anterior border, and a marginal row of small loculi. 

 Face of bothria smooth ; edges very flexible, crenulate. In the alcoholic 

 specimens the pedicels are usually contracted, so much so, in some 

 cases, that the bothria appear sessile. The head is then broad, sub- 

 globose; the margins of the bothria are entire, but with a tendency to 

 lie in crinkly folds. The short-ribs which form the marginal row of 

 loculi and the crenulate border are prominent, especially in specimens 

 made transparent in some refractile medium. The bothria are some- 

 what triangular in shape, with the apices directed forward ; each one, 

 in fact, bears some resemblance to a cocked-hat. 



The neck is short, subcylindrical, and merges imperceptibly into the 

 body. The segments are at first indicated by fine transverse lines. The 

 first distinct segments are much broader than long ; next squarish, then 

 oblong. The entire neck and body are slender, linear, and much nar- 

 rower than the head. Mature proglottides not seen. Genital apertures 

 marginal, about posterior fourth. 



*I take advantage of the opportunity afforded by the passage of the proof sheets of 

 this paper through my hands to note that the above general observations on the mus- 

 culature of this species agree in many particulars with the more detailed researches 

 of Dr. Fritz Zschokke on P. thridax, in his admirable monograph on the Anatomical 

 and Histological Structure of the Cestods. (Iiecherches sur la Structure Anatomique et 

 Histologiquc des Cestodes. Me"m. Inst. nat. Gen6v. Vol. XVII, 1888.) 



