A description is given of a new species of Henneguya (Myxosporidia), named H. tegidiensis sp.nov. It is parasitic in the freshwater fish, Coregonus clupeoides pennantii, from Lake Bala (North Wales), producing in it intramuscular cysts.

1. A key to the laelaptid paraphages of Myriapoda is given.

2. Hypoaspis (Hypoaspis) spirostrepti Oudms is transferred to the subgenus Jululadaps. J. rotundatus Berl. is regarded as a synonym of this species.

3. Hypoaspis (Hypoaspis) indicus Vitzth. is regarded as a synonym of Julolaelaps luctator Berl.

4. Hypoaspis (Coleolaelaps) amazon is figured.

5. The subgenus Julolaelaps is defined and a key given to the species. The type species is figured.

6. Three new species are described, namely Hypoaspis (Julolaelaps) peritremalis, H. (J.) myriapodalis and H. (J.) pararotundatus.

7. A list of all the known species of Laelaptidae occurring on millipedes is given.

Laboratory studies on the embryonic and larval development of Haemonchus contortus under constant temperatures of 0·0°, 7·2°, 11°, 14·4°, 21·7° and 37° C., and varying moisture conditions were carried out. Reports of preliminary studies on Ostertagia spp., Trichostrongylus spp. and Oesophagostomum venulosum are included.

Observations showed that eggs in the same culture may behave in several ways: (1) eggs may develop at different rates; (2) eggs may exhibit intermittent stages of active and inhibited development; and (3) eggs may fail to develop and die at any stage from unknown causes.

The anatomy of Köllikeria filicollis (Rudolphi, 1819), Cobbold, 1860 (Trematoda: Digenea) is described in detail.

An account is given of the integument and musculature of the worm and the structure of the cyst in which it is found, followed by a discussion of the body wall in other digenetic trematodes. The alimentary canal, excretory system, nervous system and genitalia are also described.

The study shows that the sexes are not entirely separate in all members of the genus Köllikeria as hitherto believed.

The systematic position of K. filicollis is discussed and a specific diagnosis is given for the species.

The external features, the excretory, nervous and genital systems of Phyllobothrium sinuosiceps sp.nov. (Cestoda: Tetraphyllidea) from Hexanchus griseus are described in detail, particular attention being given to the genitalia.

The species is compared with Phyllobothrium dohrnii, a well-known cestode.

The systematic position of P. sinuosiceps is discussed and the differences between P. sinuosiceps, P. lactuca and P. radioductum are tabulated.

The simple arrangement of the nervous and excretory systems, the specialized features of the genitalia and host distribution suggest that P. sinuosiceps may be one of the most primitive species belonging to the family Phyllobothriidae.

The life cycle and pathogenicity are described of a pure strain of Eimeria isolated from turkey poults in Great Britain and identified as E. meleagrimitis.

There were three schizogony cycles followed by a sexual generation.

The coccidium produced a high mortality and loss of weight in young poults.

An age resistance developed by the time the poults were 8–10 weeks of age.

The pathology of the infection is described.

1. Two species of Allantonematidae were found parasitizing five of twelve species of Drosophila collected at Rothamsted Experimental Station, Harpenden, Herts, England.

2. H. aoronymphium sp.nov. was found in 20·8 % of D. phalerata and 4·3 % of D. kuntzei examined. Parasitylenchus diplogenus sp.nov. was found in about 5 % of D. subobscura, D. obscura, and D. silvestris examined.

3. The type species and taxonomy of the genus Parasitylenchus are discussed.

4. The life history of H. aoronymphium is typical of most allantonematids except that the female is fertilized when she is a fourth-stage larva. P. diplogenus has two sexual generations per cycle.

5. Both nematodes have a precocious development of the male and a retarded development of the female genital system. Both destroy host gonads.

6. The specificity of the nematodes is not a result of dissimilar ovipositing habits of the hosts, but shows a similarity to the taxonomic assignment of the hosts to subgenera.

Bacteria-free cultures of E. histolytica have been inhibited by specific and related antibodies in the antisera produced in rabbits. Maximal culture-inhibiting antibodies were produced when the rabbits were immunized with frozen and thawed, formalin-treated trophozoites injected intravenously. Human sera from subjects with current or past histories of amoebiasis also inhibited growth of amoebae in vitro.

The new species described here, found in the collections of the Chicago Natural History Museum, was forwarded to me by Harry Hoogstraal, NAMRU-3, Cairo, Egypt, for description. All measurements are given in millimetres.

Neodiplostomum intermedium n.sp. from the small intestine of the allied rat, Rattus assimilis, is described. It can be separated from other species of Neodiplostomum by the following combination of characters: genital cone absent; vitellaria form two ventro-lateral bands in hindbody without terminal masses; anterior testis nearly symmetric, as wide as posterior testis. It is proposed that Fibricola be made a subgenus of Neodiplostomum containing the species in Fibricola and the species, N. intermedium described herein, because N. intermedium is intermediate between Neodiplostomum(Neodiplostomum) and Fibricola. Further evidence is given in favour of the invalidation of the subfamily Alariinae.

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.

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.

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.

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.

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. 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.

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.

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.