This collection of parasites was made in Cyprus between February 1928 and August 1929. Some were collected by Professor R. T. Leiper personally while on a visit, the remainder were sent to the Helminthology Department of the London School of Hygiene and Tropical Medicine by Dr. R. J. Roe of the Civil Veterinary Department in Cyprus. The two collections are here dealt with together. The hosts from which the parasites were taken are as follows:—horse, mule, pig, dog, cat, sheep, goat, hedgehog and fowl. Altogether the collection comprises 16 genera and 21 species of Nematoda: 5 genera and 7 species of Cestoda: and some acanthocephala, linguatulids, ticks and sarcocysts. The latter three are not dealt with here. The following is a systematic survey of the specimens.

It has been held for many years that the species of Syphacia found in the field mouse (Apodemus sylvaticus) and originally described by von Linstow (1884) under the name of Oxyuris stroma is the same as Syphacia obvelata (Rud., 1802)—a common parasite of rats and mice and occasionally found in man.

Nematodes belonging to two distinct genera are known as the causal organisms of galls on the roots of plants. One of these belongs to the genus Anguillulina=Tylenchus and the other to the genus Heterodera. The former, under the name of Tylenchus hordei Schøyen, 1885, has been known for many years as the producer of galls on the roots of certain grasses and cereals; the latter, under the name of Heterodera radicicola (Greeff, 1872) Müller, 1884, as the producer of galls on the roots of a very large number of wild and cultivated plants both monocotyledons and dicotyledons.

The grey squirrel (Sciurus carolinensis), although of comparatively recent introduction from North America, has become thoroughly acclimatised and may now be regarded as one of the native British Mammals. Comparatively little is known of its helminth parasites and the following oxyurid, found in the large intestine of a specimen shot in the north of Scotland, appears to be undescribed.

In a paper published in 1925, the writer described the anatomy of the adults of this parasite and amplified Schøyen's account of it. At the same time it was shown that infective material derived from Elymus arenarius could give rise to galls on the roots of barley and Poa annua. Kemner (1930) has quite recently shown experimentally that the parasite from barley can set up galls on E. arenarius and presented important data on the agricultural significance of the parasite in northern Sweden. Detailed information as to which is infective stage of the parasite and on its life-history have so far been lacking and in order to remedy this omission the writer made a number of observations and carried out certain cultural experiments during 1927 and in the months of July, August and September 1931. These latter were made possible by the arrival during July of a good supply of galled roots of Elymus arenarius received in a living condition.

During a recent expedition carried out by Dr. W. K. Blackie and Mr. W. A. McDonald in Southern Rhodesia, large numbers of the snail Bulinus tropicus were collected for living storage in aquarium tanks in the Medical Zoology Division of the London School of Hygiene and Tropical Medicine. They were collected about the 20th February, 1931 and were brought to London on the 30th March and were distributed amongst several separate tanks. Some five weeks later some of the snails were overtaken by a curious sickness which gradually but rapidly spread to the rest and within a fortnight of their first appearance, the characteristic symptoms were present to a greater or less degree in almost every one of the snails, which numbered several hundreds. The sickness proved fatal in many cases and towards the end of three weeks the mortality was nearly 50 per cent. Thus it appeared likely that the whole collection would eventually be destroyed when the epidemic, as it seemed to be, spent itself with surprising suddenness and the remaining snails made a rapid recovery.