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.