Some Ascarids in the British Museum (Natural History)

Abstract

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 É. Blanchard (1849) describes and figures under the name of A. salaris 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.