468 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [16] 
elongated and is surrounded by a layer of longitudinal fibers. In the 
head, outside of the ring of tissue which limits the central space, there 
inay be seen in the sections both the cut ends of longitudinal fibers and 
also the beginning of transverse fibers, 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. lactuea Van Beneden (Les Vers Cestoides, Pl. IV, 
Wigs. 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. No 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 the rostella would 
have been lost. 
Habitat.—Tiger Shark (Galeocerdo tigrinus), adult, half grown, and 
young specimens togetber in spiral intestine. July 23, 1885, Wood’s 
Holl, Mass. 
ORYGMATOBOTHRIUM Diesing. 
Bothriocephali spec. Siebold. 
Anthobothrii spec. Van Beneden. 
Tetrabothrit (Anthobothrii) spec, Molin. 
Orygmatobothrium angustum, sp. NOV. 
[Plate III, Figs. 1-3.] 
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 hellow 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 wide. Genital apertures marginal. 


Anthobothrium musteli Van Beneden, Mém, Acad. Belgique, xxv, 126 and 190, tab. 
vii, 1. 
Telrabothrium (Orygmatobothrium) versatile Diesing, Sitzungsb., xiii, 582. 
Tetrabothrium musteli Van Beneden, Wagener, Noy. Act. Nat. Cur., xxiv, Suppl., 85, 
tab. xxii, 276-278. 
This worm is near O. versatile Dies. (Revis. der Ceph. Ab. Par., 276.) * | 
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