1. Evidence is given which confirms the hypothesis of Peters (1941) that nematode eggsin McMaster slides are distributed according to the Poisson series.

2. No significant variation in egg counts due to the time of sampling was found in any of four sheep observed over a period of ten days.

3. A significant negative correlation of egg concentration with faeces output was found in three of the sheep (in the fourth it was negative but not significant).

4. The variation from day to day was relatively much less marked when the counts were expressed as total daily output than when expressed simply as eggs per gram.

5. No significant correlation was found between egg concentration and the dry matter proportion of the faeces.

6. A table derived from the Poisson formula is given to aid in the determination of the range of populations from which an egg count might reasonably have been drawn.

A pellet of sheep faeces containing eggs of Haemonchus contortus forms an adequate environment for the development of those eggs to third stage infective larvae, provided that it is kept moist. Observation shows a concentration of developing larvae on the external mucous coat of the pellet. These data suggest that optimum conditions for development would occur when pellets are separated one from another and standing on a water repellent surface, thus presenting the maximum free surface area and minimum opportunity for aggregation and hence of over crowding. The best method of recovering the infective larvae would be one that obtained larvae free from contamination without requiring them to expend energy in separating themselves from the contamination.

Les Carnivores malgaches sont rares et difficiles à capturer et, les Nématodes qui les parasitent ne sont pas encore connus. Nous désirons dédier la première espèce étudiée à la mémoire du Docteur P. L. LeRoux, en souvenir de l'amitié dont il nous honora, et en respectueux hommage à la mémoire de ce grand helminthologiste.

As far as the authors are aware, no standard technique has been described for the enumeration of infective trichostrongylid larvae recovered from faecal cultures. In experiments involving artificial infestations it is usually necessary to divide a concentrated suspension of larvae into a number of doses. In measuring the doses a dilution method may be used in which all the larvae in one or more aliquots taken from the diluted suspension are distributed on to a convenient number of slides and counted under the microscope. Alternatively, aliquots may be placed on the counting slide devised by Scott (1927). Such procedures are, however, time consuming and are fatiguing to the operator, where a large number of enumerations has to be made. They have the further disadvantage that the arbitrary dilution factor employed may result in too great a dispersion or conversely too great a concentration, either of which is undesirable from the point of view of accuracy and ease of counting.

Early literature on Red Ring disease of coconuts, caused by the nematode Rhadinaphelenchus cocophilus (Cobb, 1919) Goodey, 19C0, has been reviewed by the writer (Fenwick 1957). Little information is available however on the techniques used, and investigation has shown that the extraction of these nematodes from different types of coconut tissue presents problems which are not dealt with in Goodey's (1957) review of nematological technique. It is felt that the techniques developed by the writer for this worm might be of interest to other workers who are concerned with the extraction of very slender active nematodes from hard plant tissues.

Fourteen species of parasitic worms recovered from Adenota kob thomasi (P. L. Sclater) in Uganda, Africa, are recorded.

The morphology of two tapeworms, Moniezia monardi Fuhrmann, 1931 and Avitellina buechneri sp. nov., is described in detail and discussed.

One hundred and six trees suffering from Red Ring disease were examined and the distribution of worms plotted. The results indicate that infection can start in either the root system or in the upper part of the tree. The distribution of worms in 21 of the trees examined was consistent with the disease starting in the base of the tree; and 5 trees exhibited conditions consistent with infection starting in the upper part of the tree. Of thirteen trees, more than 20 years old, one was found to be infected in the top only; the other carried an infection in the roots and lower stem. It is concluded that the disease can start in either the top of a tree or in the root system but for reasons given in the text, it is not possible to say which is the more frequent.

1. The results of a survey of 194 Peruvian and Colombian primates for filarial infections are presented. Nine genera and 14 species of marmosets and monkeys are represented in the survey. A blood film survey revealed microfilariae in 82, of 42% of the animals. Adult worms were recovered from 21 of 61 dissected animals. The 209 adult worms belong to four species: Dipetalonema gracile, Dipetalonema caudispina, Tetrapetalonema marmosetae, and Tetrapetalonema tamarinae, a new species.

2. New host records for Dipetalonema gracile are: Tamarinus nigricollis, Cebus albifrons, and Saimiri boliviensis. Saimiri boliviensis is a new host for Dipetalonema caudispina. New hosts for Tetrapetalonema marmosetae are: Oedipomidas oedipus, Saimiri sciurea, S. boliviensis, and Ateles paniscus.

3. The adult worms and microfilaria of a new species of filarial worm, Teirapetalonema tamarinae, are described from a Peruvian tamarin marmoset, Tamarinus nigricollis.

In another publication (Fenwick, 19G3) data are presented on the distribution of infection in coconut trees infected with the nematode Rhadinaphelenchus cocophilus (Cobb, 1919) Goodey, I960. The data favour the hypothesis that the disease can start either in the root system and proceed by upward extension to the stem and thence to the petioles, or alternatively in the upper parts of the tree and proceed by downward extension through the stem to the roots, but this conclusion is arrived at by inference from the condition of trees at one given time. There is no information available on the condition of the trees at any previous time nor on what would have been their condition if allowed to stand. The writers therefore decided to make observations on a number of infected trees at weekly intervals in order to learn more about the course of the disease. To this end, trees were selected in which it was considered that the disease was in an early stage and observe its spread to other parts of the tree.

Haemonchus similis Travassos, 1914 is recorded from Fiji for the first time. The third stage infective larva of H. similis is briefly described. Attention is drawn to the similarity of this larva to that of H. contortus of sheep and some of the implications are discussed.

Brachylaemus arcuatus and Plagiorchis (Multiglandidmns) mmris are recorded for the first time from the fox and sheep respectively.

While investigating Red Ring Disease of coconuts, the authors detected Rhadinaphelenchus cocophilus (Cobb, 1919) Goodey, 1960 in the root systems of three otherwise healthy coconut trees. One of these was about seven years old; the roots and the stem were sampled five times weekly but no stem or petiole infection was detected. A similar state of affairs was detected in the second tree. In neither case over a period of several weeks was there evidence of upward movement of the worm into the stem. The third tree was more interesting: the first sampling disclosed the presence of the nematodes in only one sample of roots out of four taken equidistantly around the stem; subsequent examination showed that the infection spread through the root system in the neighbourhood of the base of the tree until at the end of one month, worms were recovered from all parts of the proximal root system and the population had increased to 100–150 worms per gm. of root: many of these were sexually mature; after a further two weeks, there was still no upward movement into the stem.

The intestinal parasite Polymorphus minutus sometimes causes severe losses of domestic ducks, but more often birds on free range are unaffected although exposed to infection. The causes of this are examined and an attempt is made to explain it. The worm has no innate seasonal occurrence, but can survive for many months in the intermediate host, by which it can also be spread for long distances along streams. The veterinary implications of these findings are considered.

The large number of species of the genus Opisthorchis Blanchard, 1895 that have been reported from different regions of the world as parasites of dog, cat, man and lower groups of fish-eating vertebrates, have generally been identified on such adult morphological characters as the size or shape of the gonads, the position and shape of the excretory bladder and the character of the vitellaria, whether in acini or in linear distribution. The validity of the allied genera, Amphimerus Barker, 1911; Paropisthorchis Stephens, 1912 and Clonorchis Looss, 1907, proposed for some of these opisthorchids, had been questioned, among others, by Tubangui (1921), Morgan (1927), Baylis (1929), Faust (1930, 1949), Bhalerao (1935), Erhardt (1935), Wallace and Penner (1939), Price (1940), Dawes (1940), Bisseru (1957) and Watson (1960).

During the summer of 1961 an opportunity arose which enabled us to study the incidence of certain helminth parasites in pigs slaughtered at Roath Abattoir, Cardiff. The studies were undertaken primarily because of the apparent lack of incidence figures concerning the helminth parasites in pigs from the southern part of the Principality. Some information was available for other regions of the Principality as Morgan (1924), Jones (1926) and Lewis (1930) have published reports on helminth parasites of pigs from Central and North Wales. Unfortunately none of these papers provided any comparative data on incidence of the various helminths, the numbers of each species in each infection and the proportion of sexes for each helminth in a given population.

While working on the cranial nerves of the Nile fish Clarias lazera Cuvier and Valenciennes, my attention was drawn to the presence of a very large number of trematode larvae on the brain. Subsequently twenty-four fishes were examined, both from the White Nile and the Blue Nile in Khartoum area in the Sudan, and twenty-two fishes were found to be heavily infected, each with several hundreds of the parasite. The parasite was identified through the help of Dawes' book—The Trematoda—and after feeding experiments, as Diplostomulum tregenna the larval stage of Diplostomum tregenna Nazmi Gohar, 1932. The parasite was found above or in front of the brain in the fat tissue, in the cranial cavity. Closer examination did not reveal the presence of the parasite in the brain tissues and its cavities, nor in the eyes, two of the most common places in which the majority of similar larvae occur. In some of the heavily infected fishes haemorrhage occurred which may suggest that the parasites reached the brain through the blood stream.

Protogynous cestodes are mostly parasites of charadriiform birds and have been reported from different regions of the world. In India Progynotaenia odhneri Nybelin, 1914 has been reported by two authors (Singh, 1952 and Singh, 1959) in the form of two separate and new species (see Discussion). The present communication is based upon a study of about two dozen specimens from an unidentified host shot in the vicinity of Bareilly, U.P. The present material, which was found to represent a new species of Progynotaenia Fuhrmann, 1909, possesses a remarkable feature in the disposition of the rostellar armature which is quite unlike that in any protogynous form so far described.

1. Acanthostomum gymnarchi (Dollfus, 1950) is redescribed and the atrophy of the right caecum and the presence of an anal pore at the end of the left caecum were observed in this species.

2. The genera Atrophocaecum Bhalerao, 1940; Gymnatotrema Morosov, 1955; and Haplocaecum Simha, 1958 are considered synonyms of the genus Acanthostomum Looss, 1899 which is here divided into four subgenera.

3. Acanthostomum bagri Thomas, 1958 is considered a synonym of A. absconditum (Looss, 1901).

4. A key to the five species of Acanthostomum found in the Sudan is provided.

Experiments involving cattle, horses, pigs and fowls are presented which are considered to give evidence that thiabendazole is highly active against the Strongyle parasites but not so active against the ascarid parasites of the digestive tract of these animals. The strongyles of cattle can be controlled with a dose of 75–100 mg./kg. and those of horses with as little as 25 mg./kg. In pigs 100 mg./kg. was very active against Oesophagostomum dentatum but this dose level was of poor efficiency against Ascaris lumbricoides. A high dose of 500 mg./kg. appeared to be necessary to control Ascaridia galli in the fowl.