A thermostable serum constituent is described which has a lethal effect on the miracidia of F. hepatica. This requires the thermolabile components of guineapig complement for its lethal action. It is apparently similar to substances present in other normal sera and which have an antagonistic action on a wide range of organisms. The mode of action is discussed.

A new species, Hymenolepis miniopteri is described. The specimens studied were recovered from the ileum of the bat, Miniopterus blepotis (Temminck, 1840) from South Queensland.

The type and cotype specimens are lodged in the Queensland Museum, Brisbane, Australia.

An examination of the type material of Dibothriocephalus medius Fahmy, 1954, was made possible by the kind co-operation of Professor Swann of the Zoology Dept., Universityof Edinburgh, where the specimens are lodged.

P. 126. For ‘Homa fish’ read ‘mud-fish.’

P. 129. For ‘Homa fish’ read ‘Mud-fish, Clarias gariepinus (Burchell).’

A description of Neoparadiplostomum magnitesticulatum gen. et sp. nov. and Neoparadiplostomum kafuensis gen. et sp. nov. is given. The material was obtained from the intestine of Crocodilus niloticus, Kafue River, Northern Rhodesia.

The genus Neoparadiplostomum which is proposed as new is closely related to all the other genera of the subfamily Proterodiplos-tomatinae, but differs from them in the nature of the paraprostate and the arrangement of the sexual ducts.

A catalogue is given of some known strigeid (Trematoda) parasites from the African Continent.

In the Summer of 1943 Dr. P. L. leRoux, to whom I am very grateful for the material, madea collection of worm parasites of ducks and waterbirds, shot near the Kalunga River, Chunga Farm, Chinsali District, Northern Rhodesia. Three genera of Trematodes are represented in this material, two of which, as far as records show, viz. Typhlocoelum and Paryphostomum, whose members are widely distributed in Asia, Europe and America, are here recorded for the first time from the African Continent. Petasiger variospinosus is recorded from a new host and a new locality.

This paper is devoted to a critical analysis and revision of the systematics of the trematode genus Opisthorchis. It is shown that there is no justification for the recognition of the genera Amphimerus Barker, 1911, Notaulus Skrjabin, 1913, Gomtia Thapar, 1930, Evranorchis Skrjabin, 1944 and Euamphimerus Yamaguti, 1941.

The generic diagnosis of the genus Opisthorchis has been amplified, and on the basis of the information available in the literature mainly, certain species in this genus are suggested to be synonyms of earlier recorded forms. A list is presented of the species recognized and the host or hosts are indicated as far as is possible.

Opisthorchis geminus is recorded from two new hosts, Plectropterus gambensis and Dendrocygna viduata.