1. The paper deals with nematodes of the genus Aphelenchus causing diseases in cultivated plants. A list of these, with the main pathological conditions to which they give rise, is set out on page 144.

2. Each parasite and the disease due to it is dealt with, and particulars are given concerning the structure of the worm, together with the symptoms and biology in each case.

3. A general discussion on the problem of the appropriate treatment of these diseases is given, and the suggestion is made that some form of heat treatment of infective soils is likely to give the best results, owing to the fact that comparatively low temperatures are lethal to the parasites.

In 1865 Leuckart described from the Cat, in Germany, a very minute Strongyle worm which he called Ollulanus tricuspis. This worm which was recorded from Britain by Cobbold (1873) and Stirling (1877), but was not properly described or figured, has occurred recently in some cats examined by the writer.

The occurrence of Ankylostomes resembling human hookworms in the domestic pig has been the subject of several recent papers, the most noteworthy being the contributions of Ackert and Payne (1922 and 1923) and Gordon (1922 and 1923).

The following communication is based mainly on material collected at the Prosectorium of the Zoological Society of London. In it there is also incorporated a study of several species in the collection of the Helminthological Department of the London School of Tropical Medicine.

It has long been held—and rightly so—that Calabar swellings are caused in some way or other by adult Loa loa moving about in the subcutaneous tissues.