822 DR, W. A. CUNNINGTON ON PARASITIC 
individual variations of form will be more than usually common 
as concerns the greatly distended bodies or the cephalic processes 
for attachment to the host, as the exact shape would seem 
without significance for the life of the parasite. Yet it is 
precisely such details which are employed for the purposes of 
classification. Thus within the limits of the genus Lerneocera 
itself it is difficult to be sure how far the specific characters 
employed will prove constant and therefore trustworthy, for 
even among the specimens that I have examined a considerable 
lack of uniformity has been observed, 
Genus LernocerA Blainville. 
It does not seem desirable to re-define the genus here, 
although the species now included in it would not strictly come 
under Blainville’s original generic description. Indeed, his 
account is based upon certain misconceptions, notably the view— 
shared by contemporary writers—of the absence of appendages 
on the body, for he says ‘‘ Aucune trace d’appendices au corps.” 
Nevertheless a number of species have been placed in this 
imperfectly defined genus, but if is open to question whether 
they should all remain there. A careful study of these forms has 
given me the impression that two or three of them may merit 
separation as distinct genera, or at least sub-genera; but without 
opportunities for a more comprehensive examination, it is im- 
possible to express a very definite opinion, and the course least 
open to objection is to leave matters as they are. 
Before proceeding to give descriptions of the new species, there 
remain one or two matters which need some explanation. It is 
characteristic of most of the species, including those which are 
described in this paper, that they exhibit the peculiar boot-like 
shape of the terminal portion of the body which was first referred 
to by von Nordmann* in his account of Z. esocina. This is 
produced, in the first place, by a protuberance immediately in 
front of the genital apertures, which forms the “ heel,” and which 
we may call the pre-genital prominence. In the second place, 
there is generally a dorsal curvature of the hindmost portion of 
the body (posterior to the genital apertures and corresponding to 
the abdomen according to Claus), which, owing to the lateral 
torsion undergone by the hinder part of the body, comes to lie 
on one side or other of the mid-line and represents the “‘ toe.” 
This explanation of the appearance we owe to Claus‘, but the 
matter is made yet clearer by the conceptions on torsion in the 
Lerneide quite recently put forward by Quidort. The latter 
assumes that the torsion is the direct result of the mode of 
fixation of the parasite and the mechanical reaction of the 
external medium. Admitting the probability of this statement, 
and admitting that the orientation of a parasite to its host is 
* Op. cit. p. 124. 
7+ Vide “ Beobachtungen tiber Lerneocera,” etc., p. 2. 
= Comptes Rendus Acad. Sci. Paris, Tome 154, 1912, p. 87. 
