574 
Cestodes from Selachians 
slit. The vas deferens and vagina pass between the dorsal and ventral 
longitudinal excretory canals and ventral to the nerve cord. 
The female organs are all still young and are presented by cellular 
masses. The ovarian Anlage is situated posteriorly 
in the segment and consists of the right and left 
lobes united in the middle. 
The nerve cord is 0-033 mm. in diameter, and 
runs longitudinally between the medullary and corti¬ 
cal fields. 
Musculature. The longitudinal muscles consist of 
two sets, the one running just beneath the surface 
(dermal muscle), the other between the marginal and 
median fields. The dermal muscles consist of about 
150—160 bundles of fibres which are smaller than 
those of the inner set. The latter set consists of 
about 40—50 bundles, each measuring 0-02—0-04 mm. 
in diameter. The bundles gradually decrease in size 
laterally the median portion being the largest. 
Affinities. This worm cannot be referred to 
a known species. It shows a slight resemblance to 
Calliohothrium farmeri Southwell in the shape of the 
head. Southwell writes : not only are the bothridia 
“sessile, but they are united together for some 
distance along their length in such a way that the 
anterior view of the head is almost that of a 
square. Each bothridium extends to the centre of 
the head, becoming produced or lumpy anteriorly, 
so that all four remain distinct. Between the 
centre of head and each pair of hooks there is 
a minute accessory papilliform sucker....” In these 
respects my specimens differ from Southwell’s, that 
is, all the bothridia are so closely aggregated that 
there is no space between any two adjacent bothridia, 
and only a small area is found at the apex of head 
n.^sp. ^'x *^*”*“* between their anterior tips. The accessory suckers 
of each bothridium are three in number in my species, 
while there is only one sucker in C. farmeri. The hooks of C. farmeri 
are described and figured by the author (fig. 3 a PI. V) as simple, 
though in his fig. 3 h, PI. V, they are shghtly bifurcated. 
If the features of head : bothridia and hooks, length of worm. 
