S. Yoshida 
583 
Bothridium Hook Access, sucker 
Each bothrid. pro- 4 single to each 1 or 3 access, suckers 
vided with 3 loculi bothrid. in eeich bothrid. 
Do. 2 single hooks whose No access, sucker 
base is continuous 
Do. 2 bifurcated hooks 1 or 3 access, suckers 
(1 pair to each to each bothrid. 
bothrid.) 
From the above table, it will be seen that our worm differs from 
two genera, Calliobothriuni and Acanthobothrium, by the number and 
form of the hooks, but agrees with them in the feature of the bothridium 
and in the possession of one accessory sucker. The worm agrees 
with Onchobothrium in the character of bothridium and in the number 
and form of the hooks, but it differs froin this genus by the presence 
of an accessory sucker and by the paired hooks being connected basally. 
Thus, so far as the characters of the head are concerned, it is diflhcult 
to refer it to a known genus. At first I thought of establishing a new 
genus for it, but now prefer to place it in the genus CalUobothrium 
because: 
(1) The features of bothridium and the presence of one accessory 
sucker agree with the generic characters; (2) in this genus, we find 
that'the hooks vary in number and shape (e.g., C. aetiobatis Shipley, 
from Aetiobatis narinari Euphras., is provided with a single pair of 
bifurcated hooks; C. farmeri Southwell, from Trygon walga, is pro-vided 
with a single pair of hooks); (3) each of the two hooks has a small 
lateral process, which may represent an independent hook in Callio- 
bothrium ; (4) all the other generic characters agree. 
Besides the characters above enumerated the folding of the posterior 
segments differentiates our worm from any other species belonging to 
the genus. 
Diagnosis. Length 55—80 mm. or 110 mm. Head subquadrate 
1-0—1-5 X 0-7—0-8 or 1-2 mm. Bothridia four in number, subellip¬ 
tical, each divided into three loculi by two transverse costae, the anterior 
loculus largest, the posterior smallest. A single pair of simple hooks 
on each bothridium, anteriorly on the anterior loculus; hooks dark 
brown in colour, thorn-like in shape, the one hook slightly larger; each 
hook accompanied by a small lateral process embedded under the surface 
and invisible externally. One accessory sucker situated on the anterior 
subtriangular pad of each bothridium. Head distinctly separated from 
strobila by the neck which is tolerably long. 
Segments always broader than long; their breadth gradually 
Genera 
CalUobothrium 
Onchobothrium 
A can thobothr ium 
