1912. ] J. HorNELL: Cestodes from Indian Fishes. 199 
Neck very long and slender, proglottides very numerous, 
lateral margins lightly curved, posterior slightly overlapping, 
usually twice as broad as long, except a few of the most posterior. 
Length when alive up to 25 cm. Breadth of head under I mm.; 
of typical proglottides, 0°75 to o°9 mm. 
Habitat :—The large intestine of Uvogymnus asperrimus (Bl. 
Schn.). 
The characteristics of the genus Prosthecobothrium may now 
be amended as follows :— 
Scolex with four elongated sessile bothridia divided by trans- 
verse coste into three loculi; no accessory suckers on the anterior 
margins of the bothridia; a pair of double hooks on the anterior 
margin of each bothrium. 
BALANOBOTHRIUM, n. gen. 
Scolex acorn-shaped, consisting of a bulbous head surrounded 
at the base by a cup-shaped mobile membranous collar; a pair of 
very minute two-pronged uncini situated at four equidistant points 
on the upper circumference of the head, a minute acetabulum 
above each pair of uncini. Neck extremely short. Strobila 
ligulate, the proglottides short and wide. 
(2). BALANOBOTHRIUM TENAX, 0. Sp. 
(Pl. ix, figs. 4-6 and 8-10, and x, figs. 7, II, 12). 
This species has been found on two occasions in Indian seas, 
the first in 1905, when I found several small and immature ones 
attached to the spiral valve of a Stegostoma tigrinum (Gmel.) 
trawled on the Cevlon Pearl Banks; the second, in the intestine 
of an individual of the same host trawled in the Bay of Bengal by 
the Bengal Government Fishery Steamer ‘‘ Golden Crown.’’ 
Those obtained by the ‘‘ Golden Crown ’’ are much the larger and 
appear to have reached full development. In the dead condition 
they attain a length of 32 to 33 cm., three of the five specimens 
being within this range; the other two are shorter, 18 em. and 
21 cm. respectively. Two of the largest are headless. The scolex 
consists of a bulbous sub-conical head contracted suddenly at the 
base to a very short and slender stalk from which a delicate 
membranous upturned cup-shaped collar is given off. In life the 
bulbous region of the scolex is wholly embedded within a sac-like 
diverticulum of the surface membranes of the host’s intestine. 
This diverticulum hangs freely within the cavity of the intestine, 
its base greatly constricted. The os of its free end is minute and 
encircles closely the constricted base of the parasite’s head bulb. 
In this way the head of the cestode is so firmly held that in 
removing the worm it is impossible to withdraw it uninjured from 
the sac and it becomes necessary to tear or cut away the sac at its 
junction with the instestine. In life the wide collar below the 
base of the head bulb functions as a suctorial bothrium, enfolding 
