468 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [16] 



elongated and is surrounded by a layer of longitudinal fibers. In the 

 bead, outside of the ring- of tissue which limits the central space, there 

 may be seen in the sections both the cut ends of longitudinal fibers and 

 also the beginning of transverse libers, which extend out into the lobes 

 of the head in dense fascicles. 



The color of living specimens is translucent white, with sometimes 

 a faint bluish tint. Alcoholic specimens are opaque, white, faintly 

 yellowish, or cream-tinted. 



This worm is near P. lactuca Van Beneden (Les Vers Cestoides, PI. IV, 

 Figs. 1-7), but differs from it in the following characters: 



The neck and anterior unjointed part of the body are broader than the 

 posterior mature segments. They are not so represented by Van Bene- 

 den for P. lactuca. The genital apertures instead of opening opposite the 

 anterior third of the body of the proglottis, as in P. lactuca, open nearly 

 opposite the posterior third. ]STo mention is made of a rostellum in P. 

 lactuca, but this difference alone would not justify the creation of a new 

 specific name, since the rostellum could be easily overlooked, or if only 

 mature strobiles were found, it is very probable that therostella would 

 have been lost. 



Habitat. — Tiger Shark (Galeocerdo tigrinus), adult, half grown, and 

 young specimens together in spiral intestine. July 23, 18S5, Wood's 

 Holl, Mass. 



Orygmatobothrium Diesing. 



Bothriocephali spec. Siebold. 

 Anthobothrii spec. Van Beneden. 

 Tetrabothrii (Anthobothrii) spec. Molin. 



Orygmatobotlirium angustum, sp. nov. 



[Plate III, Figs. 1-:;.] 



Head round-pointed in front with four bothria, which are unarmed, 

 hollowed out or boat-shaped when at rest, with anterior extremities, 

 round-pointed, slightly appressed and projecting in front and sur- 

 mounted at the apex by a supplemental disk (auxiliary acetabulum). A 

 second, larger disk lies in the center of the hollow of each bothrium. The 

 posterior end of each is rounded, broader than anterior end, usually flar- 

 ing away from the neck. Border of bothria raised, somewhat thickened 

 with entire outline. Pedicels short, neck long, narrow, marked with 

 transverse, closely parallel, slightly notched or crenulate rings, which 

 give a serrate outline to the edge. Segments long and narrow, mature 

 segments five times as long as Avide. Genital apertures marginal. 

 This worm is near 0. versatile Dies. (Revis. der Ceph. Ab. Par., 270.) * 



* Boihriocej)halu8 auriculatus Siebold, Zeitschrift f. Wissenscb. Zool., ii, 218, tab. xv, 

 1-2. 



Anthobothrium muateli Van Beneden, Mem. Acad. Belgique, xxv, 126 and 190, tab. 

 vii, 1. 



Tetrobotlirium (Orygmatobothrium) versatile Diesing, Sitzungsb., xiii, 582. 



Tetraboihrium mnstcHVim Benedeu, Wagencr, Nov. Act. Nat. Cur., xxiv, Suppl.,85, 

 tab. xxii, 276-278. 



