(70 Papers from the Marine Biological Laboratory at Tortugas. 
Each bothrium is strengthened by a strong muscular ring, with a thin, 
more or less leaf-like border, and is armed at the anterior end with a pair 
of compound hooks. Each hook consists of two unequal prongs, which rise 
from a flattened base. This basal part of the hook has a characteristic shape 
in each species. The neck is traversed by conspicuous bundles of longi- 
tudinal muscle fibers. 
This genus is separated from the genus Acanthobothrium by the absence 
of coste, and from Phoretobothrium by the character of the hooks, which 
have two instead of three prongs, and further by the absence of loculi on 
the bothria. 
The species P. globicephalum suggests in its general habit of body the 
genus Onchobothrium, but there are no coste on the bothria, as in that genus. 
It is worthy of note that the hooks of P. globicephalum closely resemble 
those figured by some authors, e. g., Zschokke, for Onchobothrinm un- 
cinatum. 
_ Diesing’s genus Cylindrophorus, based on Wagener’s Tetrabothrium sp., 
is suggested as being possibly near this, but the character of a tubular 
bothrium, as that must be understood from Wagener’s figures, indicates an 
essentially different structure from that shown by this genus. 
In like manner Diesing’s genus Prosthecobothrium (Bothrium cornutus 
Duj., Onch. coronatus Duj., Acanthobothrium, Dujardin, van Beneden, 
etc.), while resembling it in the absence of coste and in the presence of 
forked hooks on each bothrium, differs in having a foliaceous appendage 
on the posterior end of each bothrium. 
10. Pedibothrium globicephalum gen. et sp. nov. 
(Plate 2, figs. 9-16.) 
Head, especially in preserved specimens, globular. Bothria ovate, pro- 
jecting in front of hooks, and supplied with prominent marginal border; 
each armed with a pair of small two-pronged hooks. The prongs are only 
moderately curved and are of unequal size, the inner one being the shorter. 
The common base is somewhat elongated. The neck is distinct, but the 
first segments begin as faint transverse lines at a distance from the head 
equal to three or more times its length. Strong muscular bundles lie in the 
neck near the head. 
The first segments are broader than long, then squarish, then longer 
than broad, with rounded angles. Ripe segments much longer than broad, 
in some cases slightly narrowed at the extremities, especially the anterior. 
Genital cloaca on lateral margin, a little behind the middle, vagina in front 
of the cirrus, at first at right angles to the axis of the segment, then parallel 
with it to the paired ovaries near the posterior end of the segment. 
The vitelline glands form a marginal border throughout, except at the 
extremities. As a rule they extend but a short way back of the ovaries. 
