Ring-necked pheasants were exposed to artificially limited 10-day infections with heterakids either from 0-10 or 10–20 days old. The number and length of worms developing from a subsequent challenge dose were compared with those in nonimmunized control birds and with those in birds that had been exposed to a continuous immunizing infection for a total of 49 days: 28 days before challenge and 21 days during the challenge infection.

The morphology of abnormal development of the filarial worm Brugia patel in a mosquito host, Anopheles labranchiae atroparvus, is described. Development was very variable, from little growth beyond the microfilarial stage to the complete development of two infective stage larvae in one mosquito. The majority of larvae developed beyond the microfilarial stage but integrated differentiation did not occur. In the most bizarre larval development, the intestinal and the rectal cells prolapsed and then attempted to differentiate outside the body of the filarial larva. It is concluded that the abnormal development of the filarial larvae in this mosquito host is due to the host reaction elicited by the developing larvae, apparent as melanisation 48–78 hours after ingestion by the mosquito, often localised specifically over the excretory and anal vesicles.

The spatial distribution of the monogenean Dactylogyrus amphibothrium over the gill apparatus of the ruffe Gymnocephalus cernua was non-random, parasites being aggregated on certain areas of the gills. By plotting the distribution over the gills of the glochidia of Anodonta cygnea, the relative amounts of water passing over the different parts of the gill apparatus was determined experimentally. The observed distribution of D. amphibothrium was then compared with the distribution of the glochidia. The results obtained suggest that the site of attachment of D. amphibothrium is influenced at least in part by the direction and force of the respiratory current over the gills. Most parasites select a site where they are not subjected to its full force.

The taxonomic histories of Spirometra and Lueheella are reviewed, and the former is shown to be a junior synonym of the latter. Gatesius probably has priority over both. It is suggested that the International Commission on Zoological Nomenclature be petitioned to exert their Plenary Powers to validate Spirometra and invalidate Lueheella and Gatesius.

Two species of palaeacanthocephalan from Solea bleekeri from estuarine waters in Cape Province, South Africa, are described. Rhaidinorhynchus capensis sp. npv. differs from its closest relatives in having a smaller proboscis and in having body-spines arranged in a single field. Longicollum sp. innom., described from a single male specimen, differs from other species of the genus in having a basal row of large proboscis hooks and in having a recurved proboscis-sac.

The two species of palaeacanthocephalans described in this report were collected from Solea bleekeri Boulenger, 1898, in estuarine waters in the southern-most region of Cape Province and donated to the British Museum (Natural History) by Professor John H. Day of the Zoology Department, University of Cape Town. Co-infestations did not occur, nor were both species found in the same immediate geographical area. The coastal region of Cape Province, from Algoa Bay in the east, to Cape Agulhas or Cape Point in the west, constitutes, according to Ekman (1953), an independent zoogeographical province, and, therefore, data on the parasitic worms of the marine fish of this region, which at the moment are exceedingly meagre, may be of interest and importance as indicators of the affinities of the fish stocks inhabiting this area.

The redia, cercaria and metacercaria of Opisthodiscus nigrivasis from Ancylastrum fluviatilis are described. Observations were made on the behaviour of the cercaria and experimental infections with metacercariae have been carried out in laboratory-raised frogs of the species Rana ridibunda. Some features of the morphology of these juvenile stages and aspects of the behaviour of the cercaria are compared with those of others related species.

The best known biological cycles in the Diplodiscinae are those of Diplodiscus subclavatus (Pallas, 1970) Diesing, 1836, and Megalodiscus temperatus (Stafford, 1905) Hanvood, 1932. The first was described by Looss (1892), who showed that the molluscs Planorbis nitidus, Pl. vortex, Pl. rotundatus, Pl. spirorbis and Pl. contortus acted as intermediate hosts. More recently Milka (1970) found young forms of D. subclavatus in Pl. planorbis and gave a brief description of the redia and cercaria of this species.

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.

Pelecitus galli n.sp. is described from the Malayan jungle fowl Gallus gallus spadiceus. It differs from other species of the genus in the size of the spicules, number and arrangement of caudal papillae in the male, and the relative position of the vulva. It is also the first species of Pelecitus described from the genus Gallus.

Three types of microfilariae were seen in blood and lung smears of two jungle fowls trapped in Tasek Bera in Pahang State. One of these microfilariae is indisguishable from that described by Dissanaike (1963) from the Ceylon jungle fowl. One of the other two resembles the microfilaria of Pelecitus ceylonensis described from Ceylon (Dissanaike, 1967) and adults were found between the tendons at the bases of the legs of one of the jungle fowls examined.

A comparative study on the pathogenicity of two strains of Schistosoma mansoni one from Bor District and the other from the Gezira in the Sudan, using Cercopithecus aethiops monkeys as experimental hosts. The results, which were based on the assessment of various clinical, parasitological and pathological parameters, indicated that Bor strain was responsible for a more severe type of disease than its Gezira counterpart. Monkeys infected with Bor parasite generally revealed higher worm and egg loads, more marked changes inHb content and body weight gain and more extensive lesions in the liver and two monkeys died.

In the Sudan, it has often been noted that the disease produced by Schistosoma mansoni, as observed among patients from Bor District in the Southern Region, is far more severe than that usually encountered in those from the Gezira in the northern part of the country. These two areas which are about 500 miles apart differ widely in their climate, indigenous population, and social and economic status. It has been suspected that differences in the pathogenicity of the local S. mansoni strains may be one of the important factors determining the clinical presentation of the disease. Accordingly, a comparison of these two strains was undertaken, using the green monkey, Cercopithecus aethiops, as an experimental model. These animals varied in their response to the schistosomal infection, irrespective of the strain used, but the group infected with the Bor strain generally suffered from a more severe illness than their counterparts infected with the Gezira form of the parasite. This was evidenced by the higher worm and egg loads, and consequently the more severe clinical and pathological effects shown by the former group.

Histological and gross changes in the lymphatics of cats singly or repeatedly infected with Brugia pahangi were studied chronologically over a period of 5 years. Lymphatic dilatation occurred within 2 weeks of injection and an initial acute inflammatory reaction in the lymphatic wall and lumen was followed by chronic inflammation within 4 months. In some long-term repeatedly infected cats, the lymphatics became non-functional fibrous cords and conditions of oedema and early elephantiasis, similar to those seen in early human filariasis, were produced. The main points of contention in the study of filariasis which were cluciaated in this system were: (1) that living worms cause lymphatic damage, not exacerbated by their death; (2) that lymphatic damage is not progressive after a certain peak of reaction is reached, except in repeatedly challenged animals; (3) that microfilariae do not appear to cause lymphatic damage.