Larval nematodes occurring in cysts in the body musculature of Icelandic cod have been identified as belonging to Porrocaecum Raillet & Henry, 1912 (subgenus Terranova Leiper & Atkinson, 1914), probably P. decipiens Krabbe and Anisakis Dujardin, 1845. Identification was made possible by rearing them in vitro to the pre-adult condition. The experiments show that the following conditions are necessary for the moult to the pre-adult state; (1) a fairly high culture temperature (37° C.); (2) the presence of pieces of fish for 24 hr. towards the beginning of the culture period. 1 % pepsin, while it assists the hatching from the cysts, is not essential for the moult to the pre-adult condition. Experiments indicate that the moult takes place 3–5 days after fish has been supplied.

The larvae and pre-adults of both genera are described. Samples of larvae from cod from Greenland and the Barents Sea probably consist only of Porrocaecum and Anisakis, but a sample from West Scotland contained only Porrocaecum. The significance of the moult to the pre-adult state is discussed.

Of the two specimens of the little grebe, Podiceps ruficollis Vroeg shot in the environs of district Pilibhit, U.P., one harboured two mature specimens of the genus Schistotaenia Cohn, 1900 and a large number of specimens of the genus Tatria Kowalewski, 1904. Study of these specimens has shown that the former is a new species. So far as the author is aware, this is the first record of amabilid cestodes from India.

1. Moles were collected from four main areas, Suffolk, Cheshire-Staffordshire, Westmorland-Yorkshire, and south-west Scotland, and examined for the presence of flukes. Three species were found: Itygonimus lorum from all the areas (and in one mole from Oxford); I ocreatus from Suffolk; Omphalometra flexuosa from Suffolk and Cheshire-Staffordshire.

2. The sex of the host has no effect on the incidence of parasitism with flukes.

3. I. lorum is almost exclusively a parasite of the lower half of the intestine, whereas I.ocreatus and O. flexuosa are predominantly parasites of the upper half of the intestine.

4. The commonest number of flukes of any of the three species to find in a mole is one, though two individuals is almost as common a number in the case of I. lorum. Nevertheless, large populations of I. ocreatus or O. flexuosa and moderate numbers of I. lorum are on occasion found in one mole.

5. Premunition does not occur with infestations of I. lorum and probably not with I. ocreatus and O. flexuosa.

6. The distribution of each species even within an area where it occurs is very patchy and local. This is probably bound up with restricted movement of the hosts, whether final or intermediate, and may also be associated with the influence of soil conditions on the intermediate hosts.

7. There appears to be no seasonal variation in the presence of flukes in moles.

8. Simultaneous infestation with more than one species of fluke is rare. It is possible for O. flexuosa to live in company with I. lorum or I. Ocreatus, but the two Itygonimus species were never found together in the same mole.

9. The presence of flukes in a mole has no effect on the rest of the intestinal helminth population of the host.

The New World iguanid lizards of the genus Sceloporus are parasitized by the scale-mite Geckobiella texana (Banks) 1904. This species has been sufficiently described by Banks (1904, 1906, 1907, 1915), Hirst (1917, 1926), Lawrence (1953) and Lane (1954), while the life history has been worked out by Goodwin (1954).

Antibody-resistant strains are less sensitive to suramin and antrycide than antibody-sensitive strains. When living trypanosomes were exposed to suramin and antrycide in vitro, antibody-resistant strains needed 50 times more drugs than antibody-sensitive trypanosomes in order to make them non-infectious to mice. In therapeutic experiments in mice the minimal therapeutic dose of drugs for antibody-sensitive strains was 0·1 mg. but for resistant strains it was 0·3 mg./20 g. mice. Rabbits treated prophylactically with suramin resisted infection with the antibody-sensitive strain for a period of 4 months, but failed to resist infection with the antibody-resistant strain after 2 months.

Rabbits treated prophylactically with antrycide pro-salt, resisted infection with antibody-sensitive strains for a period of 2 months, but failed to resist infection with the antibody-resistant strain even 1 month after injection with the drug. Although trypanosomes can become drug resistant without being antibody resistant it is suggested that, under natural conditions, drug-resistant strains in animals and man develop from antibody-resistant strains, particularly when trypanostatic drugs are used. It is suggested in conclusion from these experiments that strains of trypanosomes which are exposed for some time to antibodies and become antibody resistant after passage through animals like rabbits, as well as those strains frequently passaged through mice, should be used in all tests for the efficiency of chemotherapeutic drugs.

1. The morphology and life cycle of a new microsporidian, parasitic in the mid-gut epithelium and caeca of the larvae of Scatopse notata, and also present in the pupae and flies, is described.

2. The name Plistophora scatopsi sp.nov. is proposed.

The nervous system of the female of Thelastoma bulhõesi is described. Three granular lobed structures, presumably arcade cells, are present at the anterior end of the female and of the male.

A new genus, Sprostonia, is erected in the Family Dactylogyridae, subfamily Tetraonchinae, from the study of trematodes of some Indian freshwater fishes, from Lucknow, India. The new genus differs from allied genera by the characteristically two-piece shape of the ventral bar, the articulation of the cirrus and accessory piece together at the base and the presence of a dextral vagina. The genotype S. indica sp.nov. was recovered from the gills of Eutropiichthys vacha. Three other new species, S. wallagonia, S. gomtia and S. asiatica, were also recovered from other Indian fishes and assigned to the new genus. The text is illustrated with twenty-one camera lucida figures and is followed by a key to the species of the new genus, Sprostonia.

Parasites resembling Histomonas mealagridis have been seen in a young larval Heterakis gallinae.

In a recent issue of Parasitology, I have described (Jain, 1959) a new genus of freshwater Tetraonchinae, Sprostonia, from the gill filaments of some Indian fishes. In a personal communication Dr Nora G. Sproston has kindly pointed out to me that the same name has been used by Bychowsky in his monograph on Monogenea (1957), published by the Institute of the Zoological Academy of Sciences of the U.S.S.R., for Sprostonia squatinae (MacCallum, 1921) which he makes genotype and removes it from Trochopodinae to a new subfamily Megalocotylinae in Capsalidae. I therefore change the name of the genus which I have described to Neosprostonia, Sprostonia being preoccupied.

1. Studies, using serial sections and a method of numerical assessment of the, numbers of cercariae in the various tissues, have shown that cercarial entry occurs through the skin at any point along the length of the fish and also through the gills and pharynx in the head region. The distribution of penetration along the length of the body is not uniform but exhibits a marked concentration in the head region.

2. As the time after infection increases, this initial unimodal distribution is maintained and becomes even more restricted.

3. Nearly all the cercariae have localized in the eye 12–24 hr. after infection. The few that remain outside the eye after this period appear to be moribund and undergoing phagocytosis.

4. The majority of migrating cercariae are present in connective tissue and muscle. Very few occur in the blood system and even fewer in the other organs of the body. The numbers in the blood system show a local anterior concentration in the blood vessels anterior to the heart and in the region of the gills. It seems probable that the blood system does not form the major route of migration.

5. Entry into the eye may occur at any point.

6. Cercarial migration causes extensive tissue damage, but this is fatal only when major blood vessels are perforated and severe internal haemorrhage results. Interference with the nervous system and lateral line system may be the cause of the orientation disturbances which are sometimes noted within 12 hr. after infection.

7. It is suggested that migration through the tissues is achieved mainly by the action of the anterior spination and that the function of the penetration gland cells may be lubricatory and/or adhesive rather than lytic.

8. The restricted tissue distribution during migration and the retention of an essentially unimodal distribution of cercariae along the length of the body through-out the whole period of migration suggest that localization in the lens is not achieved by chance migration.

(1) Eight species of furcocercous cercariae have been found during a 3-year study of the trematode larvae harboured by certain fresh-water molluscs in Glamorganshire. Of these four are new species, two have previously been reported from South Wales by Rees (1932) and the remaining two species have been recorded in Europe but not in Britain.

(2) Detailed descriptions are given of the four new species and the last two species which had not been completely described hitherto. The life cycles, as far as are known, of all the the species are outlined; the mollusc hosts are listed and for each cercaria a comparison with related species is given.

(3) C. hamburgensis Komiya has been proved experimentally to be the larva of Apatemon gracilis minor Yam. and according to the law of priority becomes C. a.g. minor.

1. Ditrachybothridium macrocephalum gen.nov., sp.nov., is described.

2. The systematic position is discussed and the species compared with species of the genus Echinobothrium to which it seems to be fairly closely related.

Human anti-A and anti-B and pig anti-A agglutinins were neutralized by Ascaris lumbricoides materials.

The infection of pigs with A. lumbricoides stimulated the production of anti-A agglutinin but this agglutinin appeared to have no protective action.

Oesophagostomum dentatum infection in pigs did not affect the anti-A agglutinin levels.

During the period extending from February 1955 to January 1956, 192 specimens of deer mice, Peromyscus maniculatus sonoriensis (LeConte), 174 specimens of white tail antelope ground squirrels, Citellus leucurus leucurus (Merriam) and 154 specimens of Ord kangaroo rats, Dipodomys ordii pallidus (Durrant & Setzer), were examined to determine louse-host associations, rate of infestation, frequency of distribution and seasonal fluctuation of louse populations.

Five species of lice were recovered from three species of rodents. The dominant species on the deer mouse was Hoplopleura hesperomydis (Osborn). The dominant species on the white tail antelope ground squirrel was Neohaematopinus citellinus Ferris. The only louse species recovered from the Ord kangaroo rat was Fahrenholzia pinnata K. & F.

Infestation on rodents was recorded on the basis of percentage of hosts infested, number of lice per host and number of lice per infested host. The highest number of lice per host was 27·7 Neohaematopinus citellinus per infested white tail antelope ground squirrel. The lowest value was 2·5 Polyplax auricularis per infested deer mouse.

Approximately 80 % of the rodent sample had less than 25 lice per host. This grouping accounted for about one-half of the total number of recovered lice.

Seasonal fluctuations of louse populations on deer mice, white tail antelope ground squirrels and Ord kangaroo rats were studied over one complete year. There appeared to be some coincidence between rodent activity, temperature and louse populations.

Owing to inadequate and conflicting descriptions, there have always been doubts about the identity of Trypanosoma dimorphon, which is commonly regarded as a synonym of T. congolense. However, the occurrence of atypical strains, with characters like those of T. dimorphon, has re-opened the question of the possible independence of this species.

To solve this problem, the author has undertaken a complete revision of T. dimorphon, based on Laveran and Mesnil's original type-material. In the course of this work, a total of 1200 trypanosomes, belonging to samples taken from animal passages in the course of 4 years, were studied biometrically and morphologically.

The reactions of the pigeon louse Columbicola columbae to temperature, smell and contact have been tested in a circular, glass-walled arena divided into two halves. The thermopreferendum has been found to be between 33 and 36° C, and higher temperatures are more strongly avoided than lower ones. The louse prefers cloth that has been in contact with pigeon feathers to clean cloth. Kerosene serves as a repellant. When the louse is offered different surfaces, namely, glazed paper, tin foil, blotting paper, unglazed paper, voile, silk or wool, the woollen surface is preferred most.

Three mechanisms of orientation, klinotaxis, klinokinesis and orthokinesis appear to contribute to the normal behaviour of the louse. Under certain conditions negative orthokinesis also affects the behaviour.

Comparison of the behaviour of the pigeon louse and human louse has shown that in many respects their behaviour is similar and that their thermopreferendum depends on the body temperatures of their respective hosts.

A description is given of the life history and pathogenicity of a species of Eimeria, derived from a single oocyst infection in a coccidia-free bird, and subsequently identified as E. meleagridis.

There are two asexual generations followed by the sexual generation. The first schizogony cycle occurs in the small intestine and the second and sexual generations are restricted to the caeca.

The organism is not pathogenic but the sexual stages produce marked caseous lesions in the caeca. It is immunologically distinct from a pure strain of E. adenoeides and cannot be transmitted to chickens.

In 1835 Westwood described Nycteribia sykesii and N. hopei, and mentioned the possibility of both being male and female of the same species. He also described N. dubia. In 1860 Bigot described N. oxycephala. In 1863 Kolenati created the genus Cyclopodia for N. sykesii and N. hopei, but did not include N. dubia in the new genus. Kolenati did not see any specimens, but based his diagnosis solely on Westwood's figures and very short descriptions. In 1878 Rondani described C. albertisi and N. ferrarii. In 1884 Karsch described C. greeffi and in 1889 de Meijere described C. horsfieldi. All these descriptions, except that of C. horsfieldi, are incomplete, and the first paper dealing in detail with ten species, of which four were new, is Speiser's monograph of 1901. Since then only three species have been described (C. inclita Falcoz, 1927; C. pembertoni Scott, 1932; and C. tenuis Schuurmans Stekhoven & Hardenberg, 1938). Speiser re-defined the genus. He mentioned the pigmented eyes with two ocelli, the broad antennae, the long anterior coxae and the three rings on the tibiae.

1. The incidence, intensity of infection, rate of growth and genital development in Proteocephalus filicollis has been studied by the monthly examination of approximately 60 Gasterosteus aculeatus over a period of 2 years.

2. The existence of an annual cycle, commonly reported for cestode parasites of fish in a temperate climate, is clearly established. The most advanced stages commonly occurring are: plerocercoids (0·25–5mm.) July-November; strobilate worms with genital primordia (58mm.) December-April; mature worms (1 cm.) April-May; gravid (2 cm.) June-July.

3. No tissue phase occurs between the time the procercoid is swallowed and the mature worm develops, but there is a migration from the rectum to the anterior part of the intestine.

4. From a consideration of the seasonal variation in incidence it is deduced that the parasitic population is in dynamic balance and that approximately 1 % of worms present are lost daily.

5. No evidence to support the existence of immunity was found. The lower incidence in 1+ than in 0+ fish was attributed to feeding habits.

6. Other aspects discussed are the interrelationship of proglottid formation and appearance of genital rudiments; the structure of the egg-shell; and the intensity of infection of Cyclops with procercoids as calculated from the numerical distribution of worms in the fish host.

7. Reference is made to intercurrent helminth and protozoan infections and the effect of an epidemic of Ichthyophthirius sp. on the fish population.

I wish to thank Prof. C. M. Yonge for granting every facility for this work. My thanks are also due to Mr Archer, Miss Bell, Mr Berrie, Miss Spence and Miss Wyllie for help in collecting fish, and to Mr Gray who showed me the lochan.