360 
SOME ASCARIDS IN THE BRITISH MUSEUM 
(NATURAL HISTORY) 1 . 
By H. A. BAYLIS, B.A. (Oxon.). 
(With Plates XIV—XVII.) 
1. Ascaris [= “ Agamonema”] capsularia Rud. and its probable 
adult form, Ascaris decipiens Krabbe. 
An examination of a considerable number of specimens of larval 
Ascarids from the peritoneal tissues of marine fishes has led me to 
the conclusion that the great majority of these young nematodes are 
referable to a single species, Ascaris capsularia Rud. The older 
descriptions of this form are inadequate and superficial, and even by 
the more recent writers it appears to have been assumed that, as a 
larval form, it was impossible, or not worth while, to define it more 
precisely. I believe, however, that by paying attention to the internal 
structure it is possible, even at this early stage, to discover characters of 
specific importance. The imperfect recognition of these characters has 
led, it appears, to considerable confusion, and to the inclusion in the 
species of some forms which should be regarded as specifically distinct. 
A full synonymy and bibliography has been given by Stossich (1896, 
pp. 55-57) and it is unnecessary here to review the literature in detail. 
It is desirable to point out, however, that some even of the comparatively 
recent descriptions intended to refer to A. capsularia seem, in reality, 
to belong to some other form. Thus E. Blanchard (1849) describes and 
figures under the name of A. Solaris a small form, 20-35 mm. in length, 
having three lips already visible, a lateral caecum at the base of the 
oesophagus and female genital organs already developed. A. capsularia 
Rud. is included by the author in his synonymy of this form. Von 
Linstow (1878) describes a similar form, 20 mm. long, which in several 
respects seems to agree with the specimens that I have examined, 
1 Published by permission of the Trustees of the British Museum. 
