1. Two new schizogregarines are described from the gut of the polychaete worm Potamilla reniformis (O.F.M.). One of these is meanwhile retained in the genus Selenidium Giard as S. potamillae n.sp. For the other a new genus, Meroselenidium, is proposed, of which M. keilini is the type species. The life cycle has been followed in both gregarines.

2. The schizogony of Meroselenidium is characterised by the formation of cytomeres preliminary to the liberation of merozoites. In Selenidium potamillae the schizogony is more like that in S. mesnili and S. caulleryi, though there is a considerable residual body.

3. The gametocytes become attached by their posterior ends. In S. potamillae there is often a multiple association. The gamete nuclei are formed within the nuclear area of the gametocytes. Further development takes place in sea water. Isogametes have been observed in S. potamillae.

4.The gametocyst of Meroselenidium keilini is elliptical in outline and measures about 70 × 55μ. It contains some twenty relatively large spores, 27 × 15μ, the walls of which are transversely ridged; the spores are polyzoic. The gametocyst of S. potamillae is of much the same shape, but only about half the size. The sporocysts are very numerous, spherical, smooth-walled, and measure about 8·5μ in diameter. In neither species does the gametocyst contain any residual mass.

We take this opportunity of thanking the High Commissioner of India and the Delegacy of King's College for grants-in-aid received by one of us (H. N. R.) during the course of these investigations.

A Previous paper (Bishop, 1932) dealt with the cultivation of a Hexamita sp. found in the horse-leech (Haemopis sanguisugae = Aulastomum gulo). The present paper deals with the morphology and method of division of the Hexamita above referred to, which I now name H. gigas n.sp. Dobell (1909) gave a detailed history of the nomenclature of the genus, and Wenyon (1926) has dealt with the same subject and given a list of the then known species and their hosts. Two species have since been described: H. pulcher, by Becker (1926), from the caecum of the ground squirrel Citellus tridecemlineatus, and Octomitus (= Hexamita) pitheci described and figured by da Cunha and Muniz (1928) from the intestine of Macacus rhesus. Apart from the two species (Hexamita nodulosa and H. inflate) described by Dujardin (1841) from stagnant water, and in which he saw but six flagella, a single species only has been described hitherto from a non-vertebrate host. This species, Octomitus (= Hexamita) periplanetae, a small flagellate 5–8 μ in length, from the gut of the cockroach, was described by Bělař (1916); a similar flagellate from the gut of Blatta orientalis has been found by me.

For many years it has been known that the domestic fowl, together with some other species of birds, is susceptible to experimental infection by trypanosomes of the brucei group. The successful experiments were performed in European laboratories with strains whose virulence had been greatly exalted as the result of long maintenance in small laboratory animals. Infection was induced by inoculation of infected blood into the comb, the peritoneum or a vein. A natural infection of birds with these trypanosomes has, as far as I know, never yet been reported.

The parasitic nematodes described in this paper were collected by Dr E. C. Faust during his stay in China, and sent to Prof. Hoeppli for identification and study. The total collection amounts to about 500 vials, the majority of which were collected in Peiping (Peking), mainly from birds.

In most parts of the world helminth infestations are responsible for such a heavy wastage of sheep that their control has undoubtedly become one of the most important charges that devolve upon the flock-owner. It might be thought that in tropical regions suited to the raising of sheep the problem of helminth control would cease to be urgent; and that climatic conditions, the general aridity of land chosen in such countries for sheep-rearing, and its consequently smaller carrying capacity, would contribute to form an environment distinctly unfavourable both to the survival of the free-living stages of parasitic worms and to their chances of reaching a suitable intermediary or definitive host. Such areas are not usually well watered, and it certainly does result from the paucity of permanent streams and standing water that few species of trematodes are represented. Those species that do occur, e.g. Fasciola hepatica, F. gigantica, are restricted to particular localities and are easily subjected to control.

The lymph system of Zygocotyle lunatum consists of a pair of longitudinal vessels dorsal and slightly medial to the intestinal caeca with branches to various body organs. On the basis of the lymph system and host relationships of the type genus Zygocotyle, the diagnosis of the sub-family Zygocotylinae as modified by Bhalerao to contain Stunkardia dilymphosa must be revised.

Material and habitat. Various Entozoa have been recorded from time to time occurring in the body cavity of their hosts, but very few records have been made of trematodes living in the coelom of fishes. Looss (1902) gives an account of Probolitrema richiardi (Lopez) occurring in the coelom of Mustelus vulgaris and Acanthias vulgaris, and this is the only form occurring in British marine fishes to which reference can be found in the literature (Nicoll, 1915).

The following marine Ichthyobdellid leeches have been taken at Plymouth:

I.Calliobdella lophii van Beneden and Hesse, on a large Lophius piscatorius; 1 capture, 4 specimens (vide Leigh-Sharpe, 1913 and 1914).

II. Pontobdella muricata (Linn.) on various species of Raia; rare at times; moderate-sized specimens common on skates and rays in the spring and summer of 1932.

1.Cases of accelerated development of insects due to parasitism are reviewed.

2.Two new cases are recorded.

3.The phenomenon is discussed in the light of Roubaud's study of the diapause.

Male: Large, 4·00–7–75 mm. long. Salient features: Inornate; basis capituli nearly twice as broad as long; lateral angles within the anterior third and rather acute. Anterior coxae slightly prominent in dorsal view. Lateral grooves well-marked and including two festoons. Dorsal furrows distinct, the lateral somewhat comma-shaped, the median straight and continued anteriorly beyond the laterals. Punctations very numerous, usually discreet and equal in the median area which appears shagreened; few on the scapulae, lateral folds and festoons, which form a glossy border. Adanal plates with straight external border and broad, rounded posterior border; internal border slightly concave to where it joins the posterior border to form a small point in a number of specimens. Accessory plates distinct. Spiracle short with slight dorsal curve.

1. The causal agent of tick-borne fever is transmitted by the adult female and the nymphal stage of the tick Ixodes ricinus. Two female ticks are sufficient to produce infection in a sheep. The larval stage does not appear to be infective. In a limited number of experiments the disease has not been produced in sheep by the inoculation of emulsions of presumably infective ticks.

2. The disease as produced by tick infestation is characterised by a period of incubation which varies from 3 to 13 days, after which there is a sharp rise in temperature; a “plateau” type of febrile reaction follows which lasts from 6 to 22 days, the temperature gradually subsiding to normal. Affected animals usually recover. Mortality as a direct result of infection is rare, but there is evidence to suggest that tick-borne fever may predispose affected animals to death from secondary causes.

3. The blood of a sheep which has reacted to the disease remains infective for some time after the subsidence of the thermal reaction.

4. The goat is susceptible to tick-borne fever.

5. The economic importance of tick-borne fever is discussed.

Page 124, third line from below (Table I) for “Length of first 4 tarsal segments” read “Length of first tarsal segment.”