In the literature which deals with the gape-worm, Syngamus trachea, found commonly in England, its presence has been recorded from a fair variety of birds. It has been found several times in the starling—Nathusius (1837), Megnin (1883) and, among others, by Lewis (1925). Dujardin records having found it in the magpie, Corvus pica, (1845) Megnin (1883) found it in the swift (cypselus apus), green woodpecker (Picus viridis), black stork (Ciconia nigra) and in the pheasant and partridge. It has further been recovered by Lewis (1925) from the rook (Corvus frugilegus), thrush (Turdus musicus) and jay (Garrulus glandarius), while in the Ministry of Agriculture Leaflet No. 58, the sparrow and linnet are also cited as being occasional hosts, and Walker (1886) has found it in the robin. The present writers have found a closely related species, S. merulae (Baylis, 1926) in the tracheae of four blackbirds which came into the laboratory during the summer. Though these birds seem to be only occasional hosts, most of the authors stating that the infections occurred only in young birds while the adults are comparatively free from this worm, yet a high percentage of young birds are frequently found to be carrying this parasite: for instance, Elton and Buckland (1928) in a batch of 33 young rooks obtained from the Oxford district, found 31 infected, while of 8 old birds only four were infected and these only lightly. Lewis in 1926 found 35 per cent. of a sample of starlings infected but he did not notice the age of the birds. Morgan examined two nests of young starlings and found that all of one batch harboured S. trachea. He suggests that they may have become infected from the earthworms brought in by the parent birds as food.

Experimental evidence of immunity to helminth parasites is on the whole very scanty. Several workers have drawn attention to the fact that immunity can be acquired as a result of age alone. Ransom (1921) using Syngamus trachealis in chickens, Herrick (1925) with Ascaridia lineata also in chickens, Sandground (1928) with Strongyloides and Nanophyes in dogs and cats, are three examples.

de Man (1880) described the species Tylenchus macrophallus, obtained from pasture soil, and in a later publication (1884) gave a fuller account of it with drawings. Reasons are given later in the present paper for the removal of this species to the genus Paratylenchus. Micoletzky (1921) established the genus Paratylenchus containing but one species, namely, P. bukowinensis, obtained from around grass roots near Czernowitz in Bukowina. The description was based on a single female specimen which was found only after mounting in glycerine. In spite of this, however, the distinctive characters of the genus were clearly indicated and are sufficiently marked to separate it from the nearly related genus Anguillulina. Cobb (1923) gave a detailed description of the anatomy of another species, also obtained from around grass roots, under the name of Paratylenchus nanus, which he considered might be synonymous with P. bukowinensis, and a brief account of an immature form which he called P. anceps but which very closely resembled his P. nanus. In the case of both of these forms only females were found.

1. A new species of Syngamus from the pharynx and nares of domestic cats in Trinidad is described.

2. The larval development from egg to 3rd stage larva is described with particular reference to the anatomy of the 3rd stage larva.

3. An attempt to trace the life cycle of the worm by direct infection of cats with the 3rd stage larvae was unsuccessful. It is suggested that an intermediate host is essential in the life cycle of this species.

1. The life-cycle of Filaria ozzardi was studied in St. Vincent, B.W.I.

2. Culicoides furens Poey, a common sandfly in Calliaqua, where a 37·7% human infection was found, was used in the experimental infections.

3. Two hundred sand-flies, collected at Calliaqua, were given an infective feed of blood of F. ozzardi carriers. Of these flies, fifty-five, i.e., 27·5%, were subsequently found to be infected with developing stages of the parasite. The ingested microfilariae migrated within 24 hours to the thorax, where the entire morphological development takes place. In flies which were kept alive for seven or eight days, advanced stages were found in the thorax and head, and their emergence from the proboscis was induced by slight pressure on the head.

4. The development in the sandfly consists of a metamorphosis from the 1st stage or “sausage” larva to a 2nd stage larva during the first 3 to 4 days, and from this stage to a 3rd stage or infective larva on the fifth or sixth day. Two ecdyses occur during these metamorphoses, which are discussed in relation to the other human filarial parasites.

5. Five per cent. of C. furens caught at Calliaqua were found to be naturally infected with developing larvae, apparently F. ozzardi.

6. The possibility that C. paraensis, another species in Calliaqua, may also act as a vector, is not excluded.