W. Nicoll 
343 
rounded but comes to a point at the extreme tip. In an average 
specimen of 2'75 mm. length the maximum breadth is 0'36 mm. 
The cuticle is entirely covered with minute scale-like spines, most 
closely set in the neck and becoming sparse towards the posterior end. 
There is no special cephalic armature. A distinctive feature, which 
has escaped the notice of previous observers, is the presence of a pair 
of large pigment patches, one on each side of the pharynx. They 
consist of a number of points of deep brown colour, considerably 
scattered and lying towards the anterior end of the pharynx. They 
are present even in the oldest specimens. 
The oral sucker is practically terminal, although its aperture has 
a ventral inclination. Its uncommon shape has suggested to Miss Lebour 
the name for the genus. It differs from the ordinary globular sucker 
in having its posterior end drawn out and it appears as if somewhat 
constricted about its middle part. Moreover, the posterior pole, where 
the prepharynx joins on, is usually slightly introverted, forming a sort 
of papilla in the bottom of the sucker. In specimens which have died 
before being collected, a variety of appearances may present themselves. 
In many the wide-mouthed funnel shape, figured by Stossich, is seen 
and this in conjunction with other circumstances suggests that Stossich’s 
specimens had been dead some time before he obtained them. This 
would account for the absence of external seminal vesicle, spines and 
pigment patches in his figure. Frequently the sucker is found so 
greatly retracted that it is drawn quite within the body and communi¬ 
cates with the exterior only by a minute aperture. In several cases, 
again, the pharynx is found completely enclosed in the sucker and in 
one or two cases it had been actually ejected through the mouth. All 
these appearances point to a comparatively enormous muscular develop¬ 
ment of the anterior part of the body, and this again may be correlated 
with the relative weakness of the ventral sucker and the rest of the body. 
The sucker presents the further peculiarity of having the ventral border 
of its aperture notched in the middle line. This is a constant feature. 
Although the oral sucker has an elongated appearance its length is 
really not greatly in excess of its maximum diameter and frequently indeed 
it is less. In a 275 mm. specimen the maximum diameter is 0’21 mm. 
The ventral sucker is situated at a distance of 0'95 mm. from the 
anterior end and the neck is thus a little more than a third of the 
body-lengtli. The sucker is circular and fiat but it is capable of being 
raised to a small extent above the surface of the body. Its diameter is 
046 mm. and the ratio to the oral sucker is very nearly 3 :4. 
22—2 
