330 
Entozoa of Fishes 
coast for I have obtained it at St Andrews and also at Plymouth. It 
has however not been recorded from the East coast of England. The 
only other host in which I have found the species is Pleuronectes 
platessa, in which immature specimens were obtained twice. Its 
occurrence in this host is rare and is possibly fortuitous. The two 
fishes have four other parasites in common, and thus it is not altogether 
unexpected to meet a frequent parasite of the one occasionally in the 
other. 
The specimens obtained in the Clyde were all immature but I have 
since collected a number of mature individuals from the South coast. 
The following description will be made mainly from the latter. 
The species has the typical Allocread shape, broadest at the ventral 
sucker, tapering gradually towards the posterior end, which is blunt, 
and more rapidly towards the anterior end. The colour is dull greyish 
yellow. The length of egg-bearing specimens varies from T25—T75 mm. 
the average being 1*5 mm. The greatest breadth is about ^rd of the 
length. The length T25 mm. seems to represent the maturity size, for 
quite a number of specimens were observed of sizes from IT—T2 mm. 
in which egg production had not yet begun. The smallest specimen 
measured 0'32 mm. and the cereasia is evidently, therefore, of very 
small size. 
The cuticle is unarmed and there are numerous subcuticular glands 
especially on the ventral surface anteriorly. 
In an average specimen of To mm. length to which all the following 
measurements refer the oral sucker is subterminal and globular, with 
a diameter of 0T8 mm. The ventral sucker is transversely oval and 
may be raised on a pedicle in certain states of extension, as is the case 
to a greater or less extent with all the members of the sub-family. It 
is situated a little more than i-rd of the body length from the anterior 
end (0'56 mm.). Its diameters are respectively 0'29 mm. and 0'35 mm. 
The diameter of the oral sucker is thus about |th of the body length 
and the diameters of the ventral sucker ith and jth respectively. The 
ratio of the transverse diameter of the suckers is very nearly 1 : 2. 
There is a short prepharynx and a large pharynx, the diameter of 
which is more than half the diameter of the oral sucker. It is almost 
globular, the breadth being usually a little greater than the length 
(0T0 x O il mm.). The oesophagus is short, being always shorter than 
the pharynx, about 006 mm. The intestinal diverticula diverge 
widely and terminate a little beyond the testes and thus at an ap¬ 
preciable distance from the posterior end of the body. 
