The material described consists of two small collections. One composed mainly of helminths from birds, was collected by Major T. A. Cockburn, M.D., D.P.H., on the Gold Coast in 1943. The other was collected from mammals by Dr. K. Morris, of the medical department, Kumasi, in 1939. To both of these collectors and to Dr. R. T. Leiper, C.M.G., F.R.S., who kindly put the material at my disposal, I am much indebted.

The bird material contained 8 different genera, of which one is a tremtftode, three are cestodes and the others are nematodes. The Acanthocephala are not represented.

A Squacco Heron, Ardeola ralloides, yielded a number of specimens of the trematode Clinostomum complanatum (Rud., 1814), Braun, 1899. They were taken from the oesophagus where they were actively moving about at the post-mortem examination. It is a small worm between 3 and 4 mm. long, strongly muscular with comparatively large suckers. The vitellaria are abundant and so deeply staining as somewhat to obscure the other organs. It has previously been recorded as a parasite of Ardea cinerea and Nycticorax griseus in Europe, but apparently both this host and this geographical distribution are new records. The vector is a fish; Ciurea in 1911 having implicated Perca fluviatilis.

Phaneropsolus aspinosus sp. n. is described from the leaf monkey Macaca fascicularis in central Pahang, West Malaysia. Morphological characteristics are compared with both the subgenera Phaneropsolus and Primatotrema.

Laboratory-bred goldfish were experimentally infected with Contracaecum rudolphii, either directly (with nematode larvae) or indirectly via infected zooplankton. Intensity and prevalence of infection were markedly higher in fish exposed to the infected zooplankton than in goldfish exposed to nematode larvae. When transmitted to fish via the zooplankton, larvae developed much faster and, after 8 weeks, became firmly encysted in the intestine wall. The digestive tract of larvae isolated from the intestine wall showed a well-developed ventriculus, ventricular appendix and intestinal caecum. The mouth was surrounded by three lips. When free-living larvae induced infection, they rapidly penetrated the intestine wall and migrated to internal organs (e.g. liver). The primordial lips of those larvae were poorly visible, the ventricular appendix was short, and the intestinal caecum was absent. During the 10-week experiment, no encysted larvae were found in fish infected with free-living larvae.

A new genus Morgascaridia is proposed for Paraspidodera sellsi Morgan, 1927, which is redescribed.

The systematic position of the new genus, and of the genus Schneidernema, is discussed and it is suggested that both should be referred to the family Ascaridiidae.

The systematic position of the family Ascaridiidae is considered and it is believed to show greatest resemblances to the families placed by Chabaud in the superfamily Ascaridoidea, and is accordingly referred to that superfamily.

That the infective larvæ of a number of species of hookworm are capable of penetrating intact skin has been demonstrated in the following, Ancylostoma duodenale, A. caninum, A. braziliense and Necator americanus.

Intensive cropping on a commercial scale as practised on fertile land in Europe is hitherto unknown in the Gold Coast apart from the growing of cocoa trees in a wide belt stretching from east to west across the central region of the country. In general, the method of farming is exceedingly primitive, being largely shifting cultivation, that is, the bush is partially cleared and the land is then cultivated by hand-hoes and cropped for a period of three or four years. Normally, no manure of any kind, either organic or inorganic, is applied and the land at the end of this period is allowed to revert to bush. New ground is brought into cultivation in its place, only to be allowed when virtually exhausted of readily available plant food to return to its natural, jungle condition.

Venkatarayan (1932) gave a short account of the occurrence of galls on Andropogon pertusus Willd., a common pasture grass of South India. He described the appearance of the galls, their distribution on the plant, the symptoms to which they give rise and established the fact that the nematode causing them is a species of Tylenchus to which, however, he did not give a specific name. He pointed out that there were no earlier records of the occurrence in India of galls on grass or cereals due to nematodes apart from those caused by Anguillulina tritici in the ears of wheat.

The ectoparasite fauna of two damselfishes, Stegastes nigricans and Dascyllus aruanus, from Moorea Island in French Polynesia was investigated. Gills of these damselfishes were infected with congeneric Monopisthocotylea Monogenea belonging to the genus Haliotrema. Stegastes nigricans were found to harbour a guild of three Haliotrema species whereas only one species inhabited D. aruanus. Microhabitat distribution, inter- and intraspecific competition and interspecific associations on the gill were studied. Observations on site preference revealed no spatial segregation between the three congeneric species inhabiting the gills of S. nigricans. Juvenile and adult monogeneans of that guild occurred on the same microhabitat. The dominant species Haliotrema sp. 1 did not expand on the microhabitat when the intensity of infection increased. Interspecific association tests revealed positive and negative associations. Haliotrema sp. 4 expanded its distribution on the gills of Dascyllus aruanus when the intensity of infection increased suggesting the likelihood of intraspecific competition. Juvenile and adult monogeneans of Haliotrema sp. 4 appeared to segregate as a result of intraspecific competition. This competition may exist to enhance resource availability when the gill habitat is limited. Overlaps between niche breadth and species microhabitat were revealed for monogenean species inhabiting S. nigricans. Interspecific competition did not appear to play an important role in the distribution of S. nigricans congeneric ectoparasites. Reinforcement of reproductive barriers may have led to the avoidance of hybridization.

The Chemical nature and mode of stabilization of the eggshell/capsule of Moniezia expansa, Avitellinalahorea and Stilesia globipunctata have been investigated using histochemical techniques. In M. expansa Where vitelline glands are present, the eggshell is stabilized by -S-S and -S-H linkages Whereas in A. lahorea and S. globipunctata, the viteline glands are absent and the double membranes, fibrous capsule and paruterine organ contain mainly elastokeratin-type structural protein. The possible role of the vitellaria in the presence or absence of eggshell and its thickness is discussed.

Parasitological and clinico-pathological aspects of Schistosoma intercalatum infection in sheep were studied after exposure to 5000 cercariae per animal. It was shown that the infection, in spite of relatively high tissue egg counts, only gave rise to low-grade clinico-pathological manifestations with almost unaffected blood parameters. The parasites were mainly located in the lower part of the intestinal tract, and the number of eggs being passed in faeces was very low.

The kinetics of Breinlia booliati infection in 3 inbred rat strains (Lewis, Wistar and Sprague Dawley) were investigated. One group of rats was infected as neonates (less than 24 hours of age) with third-stage larvae of B. booliati and the other group was infected as juveniles (4 weeks of age). The results showed that infection in the neonates were significantly different from the infection in the juveniles. The 60 rats infected as neonates, when necropsied between 8 to 10 months postinfection, yielded adult worms. The 2 neonatal infection groups of Lewis and Wistar strains showed highest susceptibility to the infections. The mean prepatent period was 85 days. Ninety to 95% of the infected rats were patent with microfilaraemia and a large percentage (33 to 47%) of them had high microfilaraemia counts exceeding 3000 mff/20 mm3 of blood and larger sizes (mean 157·11 mm for female adult worms and 61·88 mm for male adult worms. The adult worms were distributed equally in both the pleural (57%) and peritoneal cavity (43%). In most aspects, the neonatal infection group of the Sprague-Dawley strain was intermediate in susceptibility between the 2 neonatal infection groups of the Lewis and Wistar strains and the 3 juvenile infection groups. In contrast to neonatal infection groups, the 3 juvenile infection groups exhibited low infection rates (37%, 58% and 47% for the Lewis, Wistar and Sprague Dawley strains respectively), longer prepatent periods (mean 101 days), lower recovery rates (2 to 4%), lower adult worm loads (mean 0·4 to 0·8 female worms, and 0·2 to 0·8 male worms per rat), and smaller sizes (mean 141·24 mm for female adult worms and 53·75 mm for male adult worms). Forty-four to 57% of these infected rats harboured either single male or single female adult worms in the body cavity. Most (92%) of the adult worms recovered from the juvenile infection groups resided in the pleural cavity and the remaining 8% were recovered from the peritoneal cavity. Microfilaraemia could be detected in only 3/20 Lewis rats, 5/20 Wistar rats and 5/20 Sprague Dawley rats. The mean peak microfilaraemia of the 3 pooled juvenile infection groups was 632 mff/20 mm3 of blood, ranging from 7 mff/20 mm3 to 1856 mmf/20 mm3. Our results indicate that the susceptibility to B. booliati infection in white rats is both genetic and age-associated. The responses of the 2 distinct infection groups to B. booliati infections are discussed.

The rate of glucose absorption and metabolism and the associated fluid transfer of the small intestine of rats was measured in vitro using an everted sac technique after daily doses of 0, 5, 25 or 225 infective larvae of Nippostrongylus for periods of one to five weeks. Though there were occasional significant changes in the physiology of the intestine there were no obvious patterns or trends with respect to time at any infection level. This differs from the response after a single infection. The possible role of immune adaptation and reduced immunogenicity of the worms during repeated infections is considered.

Lung infection with Angiostrongylus cantonensis was established in experimentally infected Indian softfurred rats (Millardia meltada) and Indian spiny mice (Mus platythrix). Pulmonary arterial migration occurred earlier (at day 20 after infection) in M. meltada than in Wistar rats. M. meltada and M. platythrix could serve as useful animal models for comparative studies of mechanisms determining host specificity of A. cantonensis.

The specimens described herein were collected by one of us (M.A.R.) from the stomach of Rana esculenta in Al-Basrah, Iraq. After fixation in 70% alcohol and staining in Gower's carmine, they were found to be a hitherto undescribed species of the genus Halipegus Looss, 1899 which is named here as Halipegus alhaussaini n.sp. in the honour of the late Professor A. H. Al Haussaini; Formerly Head, Department of Zoology, University of Ain Shams, U.A.R. for his distinguished contributions to the study of zoology in Egypt.

Twelve sheathbills, Chionis alba, 12 South Georgian diving petrels, Pelecanoides georgicus, and 5 common diving petrels, P. urinatrix, collected at Bird Island, South Georgia, were examined for helminth parasites. These appear to be the first helminthological examinations of birds from South Georgia. Eleven of the 12 sheathbills were infected with helminth parasites and the pattern of infection of adult male and female birds was similar. Five species of helminths were found in sheathbills, namely Gymnophallus dellciosus, Notocotylus chionis, Paramonostomum signiensis, Lateriporus australis and Corynosoma hammani. Two species, namely Tetrabothrius sp. and Stegophorus heardi, were found in both Pelecanoides georgicus and P. urinatrix.

The helminth parasites of whales and seals in the Antarctic and Subantarctic have been extensively studied, while in comparison those of birds from these regions have been neglected. As far as we are aware there are no previous reports on helminth parasites from the sheathbill, Chionis alba (Gmelin), the South Georgian diving petrel, Pelecanoides georgicus (Murphy and Harper), and the common diving petrel, P. urinatrix (Gmelin), from South Georgia.

1. Maritrema apodemicum sp. nov. from the long tailed field mouse, Apodemus sylvaticus sylvalicus (L.) on Skomer Island is described and compared with other species of the genus.

2. 14·6% of the mice were infested, the % infestation being greater in the males, 20·3%, than the females, 5·4%.

3. A brief discussion of the genus and of other species occurring in mammals is included.

This paper concerns the relationships between miracidia of Schistosoma haematobium from Aden and various species of the Bulinus complex. It includes evidence on penetration and further development within the snail as revealed in serial sections.

The relationships between the number of infective larvae (L3s) to which animals were exposed and the establishment of A. ceylanicum and N. americanus in hamsters were examined. There was no evidence of density-dependent constraints on the establishment of A. ceylanicum in the range 10–1000 larvae, but an experiment in which the range was extended to 1500 L3s gave a significant negative correlation between the magnitude of the infecting dose and percentage establishment. Even so the percentage reduction was relatively small, approximating to 0·89% per 100 larvae administered, and in practice density-dependent constraints on establishment are unlikely to affect experiments with this species in which much lower doses (<250 L3) are generally employed. The range of doses for N. americanus L3s was smaller (10–400). Of the four experiments reported, two gave a significant reduction of establishment with increasing dose and two did not. When the data was split into low doses (<100 L3s) and high doses (>100 L3s), falling establishment with increasing dose was only detected in the lower dose range. There was no difference in the establishment when doses of 100 L3s were compared with 250 or 400 L3s. On balance, it was concluded that density-dependent constraints on establishment of N. americanus in hamsters were not marked and would have little significant effect on experiments utilizing fewer than 200 L3s (approximately 7·6% reduction between 10 and 200 L3s). These results are discussed in relation to host regulation of hookworm burdens.

Second-stage larvae of Toxocara canis were maintained in vitro for one year. Susceptibility of the larvae to drugs was evaluated by means of minimal larvicidal concentration (MLC) and larval bursting percentage. MLCs of citral and decanoic acid were almost constant throughout all stages of incubation. However, bursting percentage markedly varied within the first 20 weeks of incubation. Therefore, while larvae are available for use in the MLC assay at any stage of incubation, those beyond the first 20 weeks after incubation should be used for the bursting assay to obtain reproducible results.