A new nematode, Oryctonema genitalis gen. et sp. nov., which possesses features of both the Rhabditidae and Angiostomatidae, is described from the genital system of the dynastid beetle, Oryctes monoceros O1. in West Africa. Multiplication of O. genitalis occurs in the bursa copulatrix of female beetles and the nematodes sustain themselves for long periods in the numerous aedaegal ducts of the male beetle. The possible influence of these nematodes on host viability is discussed.

The effect of irradiation on the survival, behaviour and immunogenicity of the infective (3rd stage) larvae of O. columbianum was studied. The findings reported are:

1. Irradiation with up to 160,000 r does not significantly alter the survival of the larvae when stored at 4°C and at room temperature (26–32°C) for a period of 42 days.

2. Irradiation at 15.000 r to 40,000 r results in progressively fewer adults developing but more nodules being formed in the intestinal wall. Irradiation at 80,000 r results in the larvae failing to develop and establish in the host.

Plectus murrayi n. sp. is distinguished from other species by possessing 12 lips; stoma, amphid and excretory system are ‘plectoid’ rather than ‘anaplectoid’. Eudorylaimus antarcticus (Steiner, 1916) n. comb. is proposed for Dorylaimus antarcticus Steiner, 1916 and the species is redescribed. Both species were collected from mosses from the McMurdo Sound Region, Antarctica. Anaplectus arenicola Killick, 1964 has only six lips; stoma and excretory system are ‘anaplectoid’.

1. Metacercarial cysts of Echinoparyphium serratum occur in the pericardium of the snail Isidorella brazieri. Each cyst is surrounded by a nucleated, syncytial host capsule containing granules which are presumed to be melanin. The cyst wall consists of two layers and both contain acid and neutral mucopolysaccharide but little or no protein. No modification of the cyst wall coincident with the point of emergence of the metacercaria has been located.

2. Excystment of the metacercaria takes place in two main stages when pepsin is omitted from the initial pretreatment solution: stage I (emergence from the cyst wall through the escape aperture) is an active process (exogenous enzymes are not necessary), and a high percentage of specimens reaching this stage is dependent on the combined effects of a þH of 2, reducing conditions, elevated temperature (37–39°C) and sodium cholate. Temperature and sodium cholate are absolute requirements for this stage as is pretreatment of between þH 2 and 4 when sodium cholate is included with the reductant (sodium dithionite) rather than in the excystment medium with trypsin. The possibility that CO2 is involved has not been established.

Small numbers of the nematode species: Spiculopteragia asymmetrica, Apteragia quadrispiculata, Nematodirus filicollis, Capillaria bovis, Cooperia pectinata and Oesophagostomum venulosum, were recovered from the gastro-intestinal tracts of wild Fallow deer killed in Essex. In addition, the larval cyst of the cestode Taenia hydatigena was found in the liver of one animal.

Mr. T Petre of the Volta Basin Research Project of the University of Ghana kindly entrusted the writer with some nematodes collected from the freshwater fishes of Ghana. As far as can be found from published literature there is no previous record of nematodes from the freshwater fishes of Ghana. In fact, the helminth parasites of the freshwater fishes of this country are inadequately known and only monogeneans, digenetic trematodes and a single acanthocephalan have so far been reported. This collection represents 3 different species of nematodes from various hosts, one of which is new to science and is named after Mr. Petre to whom I am most grateful

One of the morphological features that has been considered of diagnostic value in distinguishing between different strains of Schistosoma spp. is the number of testes in the male worm. Hsu and Hsu (1957) demonstrated differences in testes number between different strains of Schistosoma japonicum, and Saoud (1966) subsequently showed differences between Schistosoma mansoni from Mwanza and S. mansoni from Egypt and Puerto Rico. Significant differences in testes numbers occurred between S. mansoni from Egypt and Wellcome strains if the worms were reared in hamsters, but not if they were reared in mice (Saoud, 1966).

The variations in the oxygen uptake, reduced weight, metabolic rate and the number of contained, fully formed, healthy, autolysed or dead metacercariae, recorded during starvation in sea water, in vitro, suggest that first mainly stored carbohydrates, then mainly lipids and, in the final stages of starvation, mainly proteins are broken down and metabolised, by the sporocysts of Microphallus pygmaeus.

A new species of the genus Euparadistomum is described from the gall bladder of the domestic cat on Gemo Island, Papua. The incidence of the parasite is extremely low in the Port Moresby area, being recorded from only 1·6% of cats examined. E. pearsoni is the second species recovered from the domestic cat. A revised key to the genus is provided.

1. Helerakis gallinarum recovered from chickens, and apparently having lived exclusively or predominantly in chickens for several years, thrived better in chickens than in turkeys, when several hundred embryonated eggs were given in a single feeding.

2. Use of a smaller inoculum reduced the difference in the worm's performance in its traditional host and the new host species.

3. Performance in both species of host was the same following the feeding of small numbers of eggs from worms grown 1 generation in turkeys.