An investigation was made to determine whether British species of freshwater snail can reproduce in warm water and become susceptible to infection by Schistosoma mansoni. Twenty-seven species were cultured at 20 and 26°C, and it was found that most of them could reproduce at these temperatures. Sixteen species were exposed at the same temperature to miracidia of S. mansoni of the Egyptian, Liberian and Puerto Rican strains; a cyst was found in A plexa hypnorum exposed to the Egyptian strain, which could be attributed as being a juvenile stage of a sporocyst, but no positive conclusions can be drawn.

(1) Staining methods using paraldehyde-fuchsin, chrome-haematoxylin, and alcian blue or astra blue following oxidation, have demonstrated the shape of the hook and other structures on the cephalic space of microfilariae. These structures are described for three species of the genus Brugia, B. malayi, B. pahangi and B. patei, and are compared with the related structures found in the genera Wuchereria, Loa, Cardiofilaria, Onchocerca, Mansonella, Dipetalonema and Litomosoides.

(2) In Brugia the hook of the microfilaria is V-shaped and is supported basally by a pair of transverse basal pieces which are closely associated with an oral ring. Similar structures are found in the microfilariae of Wuchereria and Loa except that in Loa the hook is supported below by a semi-circular arch. In Brugia there is a row of three spines transversely on the cephalic space opposite the hook complex, the spines being markedly shorter in B. patei than in the other two species; in Wuchereria there is a single transverse row of four spines, and in Loa there are two or three transverse rows of spines, No spines arranged opposite the hook complex were observed in the other genera. The hook and associated structures in Cardiofilaria are similar in arrangement to those of Loa, and the small structures in Mansonella can possibly be derived from a similar arrangement. In Onchocerca the hook has the appearance of a broad plate and in Dipetalonema perstans part of the surface of the cephalic space appears to be involved with the small pointed “hook”. In Litomosoides the tip of the cephalic space is covered by a helmet-like structure carrying a pointed beak-like projection.

(3) It is suggested, from their staining reactions, that the cephalic structures of microfilariae are particularly rich in disulphide bonds, suggesting the presence of cystine.

(4) The staining methods also demonstrate an internal thread of tissue in microfilariae which extends in Brugia from the tip of the cephalic space back to the innen korper. A similar thread is present in the microfilaria of Wuchereria, Loa, Cardiofilaria and Mansonella but was not observed in the other genera, although a short thread of tissue was stained in the cephalic space in Onchocerca and Litomosoides. In Brugia, the buccal capsule, the pharynx and the pharyngo-intestinal valve develop around the pharyngeal thread of the microfilaria. The extreme end of the thread, around which the pharyngo-intestinal valve develops, differs in its staining reactions from the rest of the thread.

(5) The staining reactions of the pharyngeal thread in the microfilaria of Brugia show resemblances to those of “elastic” fibres in other invertebrates and oxytalan fibres of vertebrates. The pharyngeal thread appears to contain an acid mucopolysaccharide component.

(6) The possible functions of the cephalic and pharyngeal structures in the microfilariae are discussed briefly.

(7) A staining routine for demonstrating the structures described in this paper is given in an appendix.

The fish populations of three reservoirs and one river in the Northamptonshire area were examined over a four-year period for the plerocercoid of Ligula iniestinalis. The infection was observed in two of the three reservoirs but was not found in the river Nene. The reservoir which had no infection contained no cyprinids.

1. Ten dogs were given infective larvae of Dracunculus medinensis, originally from human cases in Western Nigeria, and bred in the laboratory in Cyclops leuckarti (Claus).

2. Parasites were found in seven of the dogs when dissected at intervals between 4 hours and 36 days. From an examination of the location of the larvae obtained, both by direct search and by the use of intravenous Evans' blue, it was concluded that they migrated directly through the tissues via the intestinal wall (about 13 hours), abdominal mesenteries (found at 7 and 10 days), and muscles of the abdominal and thoracic wall (15 days). A similar route of migration is believed to take place in cats from an examination of three positive kittens.

3. Almost no increase in length of the larvae occurred during the migration; these measured an average of 0·59 mm. in length after 15 days.

4. No moult was observed up to 36 days but one may have been missed.

Cercaria spatulata is synonymized with Holostephanus lühei on the basis of the close morphological similarity between naturally occurring cysts of H. lühei and those experimentally reared from C. spatidata in Pygosteus pungitius. Observations on metacercariae from one day to ten weeks old showed that development of the cyst is completed within six weeks. The completed cyst is wider and its internal diameter smaller than young stages, which suggests that the metacercaria shrinks during development and that the cyst expands inwards to occupy the space left. The cyst is deposited within two to three weeks and increases in width as the metacercaria contracts during development.

1. Six rhesus monkeys were exposed to 750 cercariae of a Puerto Rican strain of S. mansoni and six to the same dose of a Tanzanian strain.

2. The Puerto Rican strain proved to be much more pathogenic and during the early stages of the infection the animals infected with this strain were obviously more severely affected than the Mwanza strain animals; two died only two weeks after eggs appeared in the faeces.

3. With the Puerto Rican strain there was a shorter prepatent period and a highly significant difference in the infectivity as determined by the worm recovery. The mean maturation rate was 81% in the two fatal infections and 63·5% in the four remaining monkeys as compared with a mean of 45·9% in the 6 monkeys infected with the Tanzanian strain.

4. There were also differences in the pattern of egg output in the faeces with higher densities with the Puerto Rican strain in the initial stages but lower densities in the later stages of the infection. But it was noted that faecal egg output was a poor index of the severity of the infection. In the severely ill monkeys the faecal egg output expressed as the total egg output in 24 hours was very misleading because the affected animals had poor appetites and they passed very small quantities of blood stained mucus containing very little faecal material.

5. Tissue egg counts were far more reliable as was shown in a preliminary experiment where during a period of one week approximately 100,000 eggs were excreted in the faeces as compared with more than a million eggs retained in the tissues.

6. Details are given of the egg densities in the various organs of the monkeys. The most important difference between the two strains was the number of eggs in the liver with a mean of 1,222 eggs per g. in the Puerto Rican strain monkeys as compared with only 158·5 eggs per g. with the Mwanza strain.

7. Both groups of monkeys developed a marked lowering of the haemoglobin levels but this was not a strain characteristic and the severity was not related to the tissue egg densities. There was raised white count which reached the highest level at the time when the haemoglobin levels were at their lowest. There was an increase in the eosinophilic count in some of the animals but again this was not a strain characteristic. There was no eosinophilia in the two animals that died.

8. Fluorescent antibody levels were recorded at different stages of the infection together with the blood protein levels. The F.A. titres were at the highest levels in the acute stages of the disease. There was a significant correlation between the peak F.A. titres and the eosinophil levels in the blood. The percentage of gamma globulins in the sera showed a peak at the end of the period of observation when the F.A. titres were decreasing.

9. These observations support the clinical impression of the relatively low pathogenicity of S. mansoni in Tanzania and other parts of Central and East Africa as compared with Egypt and South America. However, the inherent pathogenicity of the strain may not be the most important factor in accounting for the differences in the epidemiology. Differences in the reaction of the human population and in the intensity of transmission are probably equally important. In Africa there is also the possibility that in some areas worm loads are reduced due to the heterologous immunity that is acquired as a result of repeated exposure to the prevalent “nonpathogenic” schistosomes of domestic and wild animals.

The position of the plerocercoid in the body cavity of rudd Scardinius erythrophthalmus was investigated. It is shown that in 6 fish out of 880 fry examined at one month old, plerocercoids occurred in the pericardial cavity and dorsal muscle tissue whereas in 733 immature fish and 220 adult fish the plerocercoid was recovered only from the body cavity. The anomalous positions of the plerocercoids are discussed, and it is suggested that the small size of the rudd fry and the short duration of the plerocercoid in the body cavity prevented site recognition, and may have resulted in the anomalous positions.

The cysticercoids of Dicranotaenia coronula and Microsomacanthuscompressa are recorded from the stomach contents of Lymnaea peregra and L. stagnalis, and M. compressa also from L. palusiris at the Wentloog level, near Cardiff, South Wales. The cysticercoids of Haploparaksis cirrosa and Kowalewskius parvitla found in the botryoidal tissue of Erpdbdella octoculata from a pool at Llynheilin, New Radnor, are described. The adults of K. parvttla reached maturity in 17 days, in a duckling, and the egg capsules produced contained approximately 100 oncospheres in each.

Infective larvae of P. tenuis given orally to guineapigs, penetrated the stomach wall and reached the body cavity. Some dispersed in the omentum extending along the greater curvature of the stomach. Others wandered into and through the liver. Some migrated through the diaphragm or along the mesentery ensheathing the hepatic vein and the vena cava. In the pleural cavity some penetrated the pericardium, and the pleura and parenchyma of the lungs. Numerous larvae were overcome by the host in the mesentery, particularly the omentum.

Infestation of the white mouse with Fasciola hepatica resulted in cumulative damage to the liver parenchyma.

Severe traumatic injury by the migrating young flukes left clearly differentiated migration pathways with progressive leucocytic infiltration. Acidophilic hyaline, necrotic patches which developed early in the infestation spread in the advanced stages to involve whole lobules while changes occurred in the bile ducts.

Electron microscopy showed intracellular changes present in both early and late stages of infestation. This was interpreted as supporting the view that a toxic element is, to a greater extent than previously recognised, responsible for the morphogenesis of liver lesions in experimental fascioliasis.

The histopathology of the livers and lungs of pigs after a primary infection with eggs of A. suum was compared with the lesions and cellular response found in resistant pigs after reinfection.

The author's previously published work on experimental infection of guinea pigs, rabbits and pigs is also discussed and summarized.

Thelandros (Parapharyngodon) tyche sp. n. (Oxyuroidea: Pharyngodonidae) is described from the caecum of the lizard, Agama stellio in Lebanon. It differs from the closest known species by the length of its spicule and the size of the eggs.

Abbreviata adonisi sp. n. (Physalopteroidea : Physalopteridae) is described from the stomach of the same species of lizard. It differs from the closest related species by the length of its oesophagus and the number and disposition of genital papillae.

1. Nine species of the genus Capillaria, namely C. aerophila, C. annulosa, C. bovis, C. brevipes, C. cholidicola, C. erinacei, C. incrassata, C. kutori and C. plica, are recorded from eight species of mammalian hosts. Measurements and figures are given.

2. The taxonomic position of the species C. bovis and C. brevipes from Ovis aries, of C. erinacei from Erinaceus europaeus and of C. incrassata from Talpa europaea is considered in the light of observations made on the material in the collection. The identity of several species resembling C. erinacei is discussed.

Many papers have been written about Wilson's snipe (Erickson, 1950), but few of them deal with the parasites of the bird. Schmidt (1962, 1963a, 1963b, 1964) working in Northern Colorado described new species of Hymenohpis, Tetrameres and Arythmorhynchus and listed the other parasites he found in a sample of 29 snipe. In the present work birds from Newfoundland, Ontario and Louisiana were examined for helminth parasites, to determine the species composition of any burden that they might be carrying and to note any differences in the species composition of the burden in birds from different geographical areas. It was also hoped to show if there was any difference in the burden carried by male and female birds.

1. An investigation of the helminth parasites of the African Darter, Anhinga rufa rufa in Ghana produced the following trematodes and cestodes:

(1) Strigea anhingae n.sp.

(2) Diplostomum ghanense n.sp.

(3) Phagicola bulbosa n.sp.

(4) Clinostomum tilafiiae Ukoli, 1966

(5) Clinostomum phalacrocoracis Dubois, 1931

(6) Echinorhynchotaenia tritesticulata Fuhrmann, 1909

The new species are described and classified in this paper.

Several kinds of data were collected from worms belonging to the genus Proteocephalus, living in the intestines of Pygosteus pungitius and Gasterosteus aculeatus.

a. Morphological data. When we compare the morphological characteristics of worms from the two hosts we find small differences in those characteristics commonly used in the descriptions of species of the genus Proteocephalus. Regularly differences of the same magnitude are used to separate species.

b. Experimental infections show that a high degree of host specificity exists in worms from the two hosts. It is impossible to cultivate worms originally coming from one host species in the intestine of the other. These experimental infections were carried out either by feeding intermediate hosts carrying plerocercoids to fishes free of infection, or by collecting worms from the intestine of one fish and introducing them into the intestine of another fish.

Experimental infections of alien hosts failed whereas infections of the proper host, carried out as controls, always were successful.

c. Mixed populations of Gasterosteus and Pygosteus living in a small closed canal system gave additional data indicating the existence of a high degree of host specificity. Throughout the year Gasterosteus showed no infection at all whereas Pygosteus was “normally” infested.

d. Monthly dissections of Pygosteus showed that in Proteocephalus living in this fish species no seasonal cycle exists similar to that found by Hopkins in Proteocephalus from Gasterosteus. The stages of development of Proteocephalus collected during the dissections of Gasterosteus correspond with Hopkins' seasonal cycle.

e. As a result of these observations it is proposed to consider the worms from Pygosteus as belonging to a distinct species. Since Dujardin was the first to describe worms belonging to the genus Proteocephalus and living in the intestine of Pygosteus as Proteocephalus ambiguus (Dujardin, 1845) this obviously ought to be the name of the species involved. The use of the name P. filicollis (Rudolphi, 1802) is restricted to material from Gasterosteus.

Oligapla manteri sp. nov. is described from the gills of Hernirham phus sp. from Noumea, New Caledonia. It differs from the existing species in the genus, O. oligapta because the atrial spines are res tricted to a circle of 16, the penis is armed with 47 anteriorly directed, pear-like spines, and the sclerotization of the copulation canal is conical. Pseudothoracocotyle scomberomori sp. nov. is described from the gills of Scornberomorus commersoni from Heron Island, and Green Island, Queensland, Australia. The new species differs from the existing species in the genus, P. ovalis, because the genital pore is not sclerotized, there are two pores to the copulation canal, and the clamps are more numerous and larger.

I should like to thank Dr. H. W. Manter of the Department of Zoology, University of Nebraska who very kindly gave me the specimens of Oligapta manteri; Dr. W. W. Becklund of Beltsville Parasitological Laboratory, U.S.A. who kindly lent me cotypes of T. crocea, and Dr. J. C. Pearson of the Department of Parasitology, University of Queensland for his help during the study.

A new method is described for the in vitro culture of the preparasitic stages of Nippostrongylus brasiliensis. It utilises the plating of faecal suspensions on to paper chromatography strips supported on non-porous Perspex slabs and has been designed primarily to facilitate savings in the time required for routine culture maintenance without lowering the quantity or quality of the larval yield. Comparison with the filter paper/Petri dish method shows an increase in larval yield of 85% and a reduction in time required for culture of 72%. Total inhibition of fungal growth on incubated faeces suspensions was obtained by the addition of “Mycostatin” (Squibb) in a concentration of 62 units per ml. or more.

Pseudanisakis rotundata (Rudolphi, 1819) Mozgovoi, 1950, from Raia radiaia in the northern North Sea is redescribed and figured with particular reference to the degree of infection, mode of attachment, the functional morphology of the genitalia and to a possible association between this nematode and a coccidian infection of the same host species. Ressons are given for rejecting Eustoma Piette 1855, as a generic name for a nematode as it is already in use for a Jurassic prosobranch mollusc.

Gemmaecaputia australis sp. nov. and Vallisiopsis australis sp. nov. are described from the gills of the striped barracuda, Sphyraena obtusata Cuvier & Valenciennes. G. australis differs from all other species in the genus by the presence of a bifurcated copulation canal and small spines on the penis. V. australis differs from the other species in the genus because of the presence of an unsclerotised penis and seven opisthaptoral clamps. The method of adhesion of V. australis is described and an account given of its adhesion on the host gills.