The following is a report on a collection of four species of parasitic nematodes from some mammals of Kwangtung Province, South China.

In this second contribution to the study of parasitic copepods of fish from Ceylon eight species are described, four of which are new. The male of one species, namely that of Euryphorus nordmanni Milne-Edwards, is described for the first time. Of the three remaining species, Caligodes laciniatus Kröyer has only been recorded once (Heller, 1865) since it was originally described in 1863 and the comparison of Caligus alalongae Kröyer and C. tenax Heller makes it easier to identify the males of these two forms.

Bassett-Smith (1898 a) described a new parasitic copepod from the gills of Cybium guttatum at Bombay and named it Helleria armata, but later (1898 b) altered the name of the genus to Cybicola as the former name happened to be preoccupied. This parasite was not again recorded until the present author (1935) redescribed the female from the gills of Scomberemorus commersoni (Lacepede) (= Cybium commersoni) and at the same time suggested the transference of this species to the genus Pseudocycnus Heller (1865). The reasons for this suggestion were based on a comparison of the female of Bassett-Smith's species with the females of the two known species of Pseudocycnus (vide Wilson, 1922). Now, however, the author has been able to obtain from the same host a male of this copepod which is here described. The evidence from this description concludes the argument in favour of the inclusion of this form within the genus Pseudocycnus.

1. An account is given of a sporozoan parasite, hitherto known as Monocystis thalassemae Lankester, and its coccidian nature is demonstrated.

2. Schizogony and sporogony both occur in the eggs of Thalassema neptuni while these are in the genital pouches (nephridial sacs). Schizogony was observed on three occasions, and only the later stages were seen.

3. The full-grown sexual parasites are vermiform and immobile. The males are smaller than the females.

4. The microgametocyte, when it becomes spherical, gives rise to very numerous, elongate microgametes, similar to those of Aggregata.

5. Fertilization has not been observed. The oocystic membrane is only sometimes formed and is always inconspicuous.

6. At all stages where a chromosome count was possible, the number of chromosomes was seven. The reduction division is zygotic. No polymitotic figures were observed either in microgametogenesis or in sporogony.

7. Numerous sporocysts are produced. These may contain as many as twelve nuclei, and presumably give rise to at least twelve sporozoites. The formation of sporozoites has not been observed by us, but was noted by Lankester.

8. A new coccidian genus, Ovivora, is created for this organism, which now becomes Ovivora thalassemae (Lankester) and is relegated to the subfamily Aggregatinae in Hoare's classification.

1. Systematic measurements of all hookworm-like eggs from time faeces of 336 patients in Mauritius led to the finding of 8 per cent Trichostrongyle, 0·9 per cent Ternidens deminutus, and 0·9 per cent Ancylostoma braziliense-like eggs.

2. This percentage of Trichostrongyle eggs includes one case from an inhabitant of the French colony, Réunion.

3. Hookworm eggs of a very small size, possibly Ancylostoma braziliense were found unassociated with the typical Necator americanus eggs, in the faeces of an inhabitant of Rodriguez; the adult worms appeared drug-resistant.

4. A partial eradication of the Trichostrongyles was obtained in one case, and an apparently complete eradication in another, of 6 patients treated with carbon tetrachloride.

5. The Trichostrongyles expelled by one of the patients were identified as Trichostrongylus axei (Cobbold, 1879) Railliet & Henry (1909).

6. No particular symptoms which could be ascribed to the action of the Trichostrongyles were observed in any of the affected patients.

7. Drugs administered orally to a patient passing Ternidens deminutus-like eggs failed to dislodge any of his worms.

1. An outline of the life history of Cephus pygmaeus Linnaeus is given.

2. The parasites of Cephus are listed and are discussed briefly in relation to the particular parasite Collyria calcitrator Gravenhorst.

3. It is shown that if the host larvae collected from wheat-stubble in autumn are used for the investigation of the extent of parasitism by Collyria, allowance must be made for the fact that the parasite Pleurotropis benefica Gahan is intrinsically inferior to Collyria, and that its cocoons must represent hosts left unparasitized by Collyria.

4. In summer the adults of Collyria emerge, on the whole, earlier than those of the host Cephus. This suggests that at the beginning of the season of oviposition there will be a scarcity of hosts in comparison with the numbers of parasites wishing to oviposit. The relative activity of host and parasite during the egg-laying period is worked out on hypotheses of the average length of life of the individuals, and is shown diagrammatically.

5. The Cephus larvae travel down the stem and hibernate at the base. When the wheat is cut, a proportion of the larvae and their parasites are removed with the straw. The way in which this may prevent the stubble material from giving a true indication of the degree of parasitism in the population as a whole is discussed.

6. On the basis that 3910 hosts receive 3600 parasites, various hypothetical distributions are worked out arithmetically in order to find which type of discrimination between healthy and parasitized hosts gives an arrangement of parasites most in agreement with what has been found for Collyria in Cephus. The most satisfactory result is that obtained when it is assumed that the probability of an already parasitized host being re-attacked varies with the proportion of parasitized hosts. It is also shown that a shortage of hosts at a time of parasite activity may cause a high degree of superparasitism, thus giving a false impression of the parasite's power of discrimination.

7. Suggestions for further field work are given.

1. Investigations into some of the problems associated with African East Coast fever and its vectors have been undertaken: and although these are, as yet, incomplete we consider them of sufficient interest to warrant their publication at this stage.

2. The present position regarding the distribution of certain tick species in relation to East Coast fever in Kenya is briefly reviewed; and outbreaks of what may be peculiar forms of the disease in sporadic areas are mentioned.

3. It is thought that the passage of Theileria parva through different species of ticks might throw light on some sporadic outbreaks of the disease and on the peculiar character of some of the cases encountered.

4. Transmission by nymphae and adults of Rhipicephalus appendiculatus, by adults of R. evertsi and R. simus is confirmed. Experiments with R. sanguineus, R. pulchellus and Amblyomma variegatum were negative.

5. Exposure of infective nymphae of Rhipicephalus appendiculatus to different degrees and conditions of temperature prove that the ticks remain infective after being subjected to 4–6° C., and 8–10° C. for 1, 2 and 3 weeks. Exposure to different alternating temperatures for similar periods had no effect on the virulence of the parasite. The ticks exposed to warm temperatures (35–38° C,) did not survive to the same extent as those exposed to cold temperatures. Ticks that survived for 1 week transmitted the disease.

6. Animals that ultimately recover from artificial infection may show a mild thermal reaction during the short course of the disease without showing typical clinical symptoms. In such cases diagnosis is frequently difficult, and Koch's bodies may be rare.

7. The association of Hyalomma spp. with many different diseases is briefly dealt with; and it is shown that Hyalomma impressum near planum P. Sch. is capable of transmitting East Coast fever in the nymphal and the adult stages after the larvae and nymphae respectively have fed on an infected animal. The parasite does not pass through the egg. H. impressum near planum is common in most parts of Kenya Colony.

I wish to record some unidentified parasites, from the abdominal cavity of a Queen Bumble-bee (Bombus terrestris).

A method is described by which active cutaneous myiasis of sheep by Lucilia sericata larvae can be produced with certainty and precision at any season of the year. The method is such that it can readily be employed in field experiments.

The material recorded and described in the present paper consists not only of the specimens in the South Australian Museum, but largely an immense number of specimens sent to the writer by Mr F. H. Taylor of the Department of Tropical Health, Sydney. To him, my best thanks are due for the opportunity to examine and describe this material. Types of the new species are in the South Australian Museum and paratypes amongst the material returned to the Department of Tropical Health, Sydney.

1. Nearly a quarter of a million eggs of Sialis lutaria were collected at Cambridge in 1936. About 0·6 per cent of them were attacked by a parasite.

2. The egg-parasite of Sialis is distinct from Trichogramma evanescens, and is to be called T. semblidis (Aurivillius).

3. The male of Trichogramma semblidis occurs in two forms. Neither consists merely of imperfect or degenerate individuals of the other, for the two forms are equally large and differ constantly and fundamentally in several characters. The species, therefore, exhibits true dimorphism.

4. Rearing experiments involving isolated pure lines show that it is principally the host that determines which form of the parasite shall emerge. Males reared on Sialis are of the apterous form; those reared on three species of Lepidoptera are of the winged form.

5. The dimorphism of T. semblidis is discussed in relation to other examples of dimorphism in the Hymenoptera. It is shown to have several features of special interest.

The paper by Apstein (1911) is the only previous work known to me which is concerned with parasites of marine pelagic Crustacea in general, chiefly Copepoda, and especially of Calanus finmarchicus. It is of the nature of a preliminary note, since his work in the neighbourhood of Kiel was suddenly interrupted in its early stages; so that, while some of his “parasites” are easily identifiable, the scanty notes on others are difficult of interpretation and have given much trouble to subsequent writers. After making observations on the parasites of Calanus in the Clyde Sea Area over a period of several years, I feel in a position to offer the following opinions on Apstein's note together with an account of very early stages in the development of some larval Platyhelminthes.

In August, 1933, I received from Colonel A. E. Hamerton, C.M.G., D.S.O., R.A.M.C. (ret.), Pathologist to the Zoological Society of London, samples of a stool obtained from an Indian rhinoceros (Rhinoceros unicornis) on exhibition in the Society's Gardens. The animal in question was at that time suffering from severe diarrhoea and wasting, and its faeces—preserved in 5 per cent formalin—contained numerous undetermined ciliates. On examination of the material I found that two kinds of ciliates were present, one a typical Entodinium (Entodiniomorpha Ophryoscolecidae), and the other an entodiniomorphous form obviously belonging to the Cycloposthiidae, but differing from all the members of this family hitherto described.