Although the morphology of the adult stage of the majority of the helminthic parasites of domestic stock is now well known there still remains a considerable amount of work to be done on the larval stages of these worms. Some of the more recent researches on the infective stage of human and other hookworms have shown that a close study of the morphology reveals appreciable differences between the larval stages of closely allied species and that the differences can be used as diagnostic characters.

In March, 1928, Mr. S. F. Ashby of the Imperial Bureau of Mycology, sent the writer some portions of diseased banana roots for examination and determination of the nematodes occurring therein. The material had come from plants growing in the Palm House at the Royal Botanic Gardens, Kew, where bananas of several species had been growing for some years in the same soil. Information was later sent that the plants had been in failing health for the last two or three years and that this year the symptoms of disease had become acute. These symptoms were said to be quite similar to those described by Nowell (1919) in the case of diseased “bluggoe“ banana in Grenada with which Tylenchus musicola was found to be associated.

A Few specimens of the Trichostrongyle, described in this paper, were obtained from the intestine of moles caught on the experimental farm of the Institute of Agricultural Parasitology, St. Albans.

The material upon which this study is based was obtained from a Red-Bellied Water Snake, Francia abacura, from Florida, which had died at the Zoological Gardens, London. This particular snake had been at the Gardens for only a fortnight before its death, so unquestionably infestation had taken place in America before transfer to London. No opportunity was afforded the writer for studying the material in a living condition and consequently the measurements were made from preserved material in the Helminthological Collection of the London School of Hygiene and Tropical Medicine.

Until now Schistosoma mansoni has been regarded as an essentially human parasite. In 1859, Cobbold recorded from Cercocebus fuliginosus a species of Schistosome which he called Bilharzia magna. The only specimen which has been preserved was found to be a fragment of a male by Leiper (1915), who states, “I have been quite unable to identify it with either of the species now recognised in man.” Various authorities have, however, referred this species to S. hœmatobium. S. mansoni has been grown experimentally by Leiper in rats, mice, guinea pigs and African and Indian monkeys, and by Lutz in rabbits. It has never been found naturally in any animal other than man.

An anæmia, resembling pernicious anæmia, has been commonly associated with Dibothriocephalus latus infection in man, but the experimental evidence in support of clinical observation has not yet been forthcoming.