Diphyllobothrium medium (Fahmy) the adult stage of which is found in the otter, Lutra lutra, is redescribed.

1. Phase-contrast, ultra-violet and fluorescence microscopy have proved useful tools in the study of the embryology of filarial worms.

2. Spermatogenesis in L. carinii has been described for the first time for any filarial worm.

3. The spermatozoa of L. carinii and D. immitis are remarkable in that they contain well defined chromosomes.

4. The development of the ovum to the mature microfilaria has been described for both L. carinii and D. immitis.

5. Staining with acridine orange has demonstrated the cellular distribution of deoxyribonucleic acid (green fluorescence) and ribonucleic acid (red fluorescence) in both living and fixed embryos of each species.

.1. Infection with Diplostomulum phoxini is very common among minnows in the Glasgow area of Scotland.

2. The first intermediate host of the parasite in this area is shown to be the freshwater snail Lymnaea peregra.

3. Adult flukes were obtained experimentally in mice, ducklings and herring-gull chicks.

4. Significant differences are shown to occur between adult flukes recovered from different host species.

5. The implications of these findings in relation to the host specificity and the classification of the Strigeida are briefly discussed.

Two distinct Diplostomulum metacercariae were shown to inhabit the eyes of sticklebacks. Both these species could complete their life cycles in the same three host species. Observations at different seasons indicated that under cold winter conditions no transmission occurred from snails to fish in the field.

(1) The microfilariae of L. loa, W. bancrofti, B. malayi, D. immitis, D. repens and D. aethiops have been studied in detail, using phasecontrast and ultra-violet microscopy and vital staining techniques.

(2) In these microfilariae the cells of the “oten Mundgebilde” have been renamed “hook-muscle cells” as they appear to be concerned with the movements of the hook.

(3) Two cells have been demonstrated in the nerve ring by means of ultra-violet photomicrography and vital staining with rongalit methylene blue.

A collection of large marine nematodes made by the Zoological Survey of Pakistan in 1959 from the Arabian Sea at Karachi revealed the presence of a new species of the genus Leptosomatum, Family Leptosomatidae. Eight females, eighteen males, and several juveniles were obtained. The species is named Leptosomatum ranjhai in honour of Dr. A. R. Ranjha, Director of the Zoological Survey of Pakistan. The following description is based on eight females and ten males. All measurements were made on specimens after clearing in lactophenol. The means for the various measurements are given in brackets.

1. The developmental stages of D. immitis in the mosquito A. aegypti at 26°C. have been followed in living and fixed preparations, and the fates of the cell groups of the microfilaria have been traced.

2. The larvae spend the first six or seven days inside the distal cells of the Malpighian tubules; during the next six days they inhabit the lumen of the tubules and eventually migrate to the head of the mosquito on the fifteenth to seventeenth day.

3. The “nuclear-column“ cells contribute largely to the formation of the oesophagus of the infective larva.

4. The G cells 1–3 produce the intestine and the G4 cell forms the anal plate and then the rectum.

5. The anal pore ultimately becomes the anus.

Drasche in Stossich established the genus Oxyspirura in 1897 for Cheilospirura cephaloptera Diesing 1861, previously described by Molin in 1800, along with two more species, all as belonging to Spiroptera. Since the establishment of this genus, as many as thirtysix species have been reported from various parts of the world. The distribution of this worm is very wide and the number of species seems to be much more than what has already been described. The writer collected nine species from the orbital cavities of birds, and all turned out to be new ones.

In 1931, Skrjabin divided the genus Oxyspirura into three subgenera, i.e. Oxyspirura, Cramispirura and Yorkeispirura, on the basis of the divided buccal capsule (Yorkeispirura) and undivided buccal capsules (Oxyspirura and Cramispirura); and also on the equal spicules (Cramispirura) and unequal spicules (Oxyspirura). The writer based the present key to the species of the genus on the same criteria. Species belonging to Yorkeispirura and Cramispirura are not included in this key.

During the course of studies on human filariasis and its vectorsin Fiji, in the period 1954–1956, (Symes, 1957) it was desirableto make a few observations on the dog filaria in order that, whenfound in mosquitoes, its larval stages should not be confused withthose of Wuchereria bancrofti from man.

Four samples of trematode parasites were collected from imported Abdim's storks at the Zoological gardens “Artis”, Amsterdam. The first collection was made during autopsy of a bird that had been in “Artis” for several years; some months later, the parasites were discovered in the oesophagus and mouth cavity of birds that were imported from Africa only recently. Ultimately, a number of trematodes belonging to the same species have been scraped out of the mouth cavities of 5 living Abdim's storks. My thanks are due to Mr. P. Zwart, veterinary surgeon, Utrecht, and to Dr. E. Jacobi, manager of “Artis”, Amsterdam, for collecting the parasites and making them available for taxonomic studies.

The material for this species consists of a slide of two worms from the intestine of Heterotis niloticus from the Sudan. The strobilae measure 4·8 cm., and 8 cm. in length. The early segments are longer than broad, but the mature segments are broader than long, measuring 900–960µ broad by 400µ long, and are 175 and 274 in number. The superficial segmentation of alternate segments is weak, and the individual segments are distinguished by the repetition of the genitalia. The genital pores are irregularly alternate and are situated at the middle of the lateral margin of the segments.

1. The gastro-intestinal tracts of 200 mink from 42 farms were examined for helminth parasites.

2. No parasites were found in the stomach but two species of fish-borne parasite were found in the intestine.

3. Evidence of infestation with the heterophyid trematode Cryptocotyle lingua was found in twelve mink, the largest number of flukes recovered from any one mink being seven.

4. Single immature specimens of the acanthocephalid Corynosonta hadweni were recovered from four mink, but it is considered that these were not instances of true parasitism.

5. It is concluded that helminth parasites do not constitute an important hazard on mink farms in Britain;

1. A new genus Sandondla is erected for the cestode Proteocephalus sandoni Lynsdale, 1960, on the basis of the position of the vitellaria in two compact bands posterior to the ovarian lobes, and Sandondla sandoni n.comb. is made the genotype.

2. A new subfamily Sandonellinae is added to the existing 8 subfamilies of the family Proteocephalidae and a key of the 9 subfamilies is given.

1. Six species of nematodes were recovered from Hertfordshire birds.

2. Porrocaecum ensicaudatum and Syngamus trachea are discussed, S. skrjabini El'perin, 1938 being considered a synonym of the latter.

3. The survey produced one new host record and two new records for this country.

1. The females of a new nematode Nilonema gymnarchi gen. et sp. nov. are described from the lung-like air bladder of the Nile fish Gymnarchus niloticus in the Sudan.

2. Nilonema gymnarchi is made the genotype of a new genus Nilonema on the basis of the presence and position of cone-like cuticular protuberances.

During the survey 571 birds, representing 22 species were examined. Of the birds examined 396 (69·3%) were found to be infected with helminths, and of those infected birds 87. (21·9%) contained trematodes, 276 (69·7%) contained cestodes, 105 (26·5%) contained acanthocephala, and 146 (36·9%) contained nematodes.

Cestodes were found in 18 (81·8%) of the species of birds examined, nematodes in 10 (45·4%), trematodes in 9 (40·9%) and acanthocephala in 7 (31·7%).

The maximum helminth infections of all the bird species examined occurred in the spring. Nestling corvids, with one exception, were not infected with cestodes, but nestling turdids were heavily infected. Fledgling corvids also differed considerably as regards cestode infection. Magpies were 100% infected, jackdaws 35%, and rooks 20% infected.

(1) The occurrence of outbreaks of Diphyllobothrium in trout and related forms is reviewed.

(2) A survey of the occurrence of Diphyllobothrium in Great Britain has been made. Plerocercoids of Diphyllobothrium have been found in approximately half of the areas from which trout have been examined. Three species of Diphyllobothrium at least have been found to infect trout and related species of freshwater fish in this country.

A study has been made of the form of the larval hooks in the coracidium and procercoid stages of Diphyllobothrium medium, D. ditremum and D. dendriticum obtained from four sources in Great Britain. It has been found that the form of the larval hooks is constant, and that hook types are related to different species. It is concluded that the hooks provide a sound basis for specific identification.

Seven species of Echinostome cercariae are recorded from London ponds and rivers. Two of these, C. Z. Rees and C. echinoparyphii recurvati Mathias have already been described from other parts of Britain. The rest are new species. C. londonensis n.sp., C. deficipinnatum n.sp. are thirty-seven spined and C. essexensis n.sp. has forty-nine spines. C. hamptonensis n. sp., and C. thamesensis n. sp. are both large-tailed Echinostome cercariae, with twenty collar spines.

The possibility of using snails as second intermediate hosts by C. hamptonensis, a large-tailed Echinostome cercaria is shown to be highly improbable.

The classification of Echinostome cercariae is discussed.