Velacumantus australis is a common mollusc along the easter and southern coast of Australia. A study of the incidence of larval trematodes in several populations of V. australis showed that the incidence of the various infections varied considerably with time and place. Heterophyids were usually the commonest infection, while schistosomes and echinostomes were frequently absent. In one population, seasonal changes in the incidence of philophthalmids and schistosomes were found to be positively correlated, and seasonal changes in the incidence of philophthalmids and echinostomes were found to be negatively correlated. These results are discussed.

The genus Citellina was introduced by Prendel (1928) for a new species, C. dispar, which he described from Citellus suslika. Since that date a further nine nominal species have been referred to the genus, thus: C. alatau Spassky, Rijikov and Sudarikov, 1950; C. alpina Jettmar and Anschau, 1951; C. bashiri Akhtar, 1956; C. levini Li, 1933; C. marmotae Manter, 1930; C. petrowi Schulz, 1930; C. schulzi Korneev, 1951; C. skrjabini Merkuscheva, 1955 and C. triradiata (Hall, 1916) Manter, 1930. Descriptions and figures of eight of these species are given by Skrjabin, Schikhobalova and Lagodovskaya (1960), who have missed only C. bashiri and had no description of C. alpina at their disposal.

1. A lower pathogenicity of the Kenya strain of T. spiralis was substantiated in mice as compared with our laboratory strain; infection with a dose of 2,000 larvae from the laboratory strain resulted in the death of all the animals, whereas 7 out of 10 and 6 out of 20 mice infected with the Kenya strain survived.

2. The reason for the lower pathogenicity of the Kenya strain is related to its weaker infectivity; after the infection with 200 larvae of the Kenya strain the number of muscle larvae produced was half (on average 17,595 larvae) that of the laboratory strain (average 32,792 larvae).

During a three year survey of the larval trematodes of Llangorse Lake, South Wales, twenty-one species of cercariae have been encountered. The Xiphidio- and Microcercous cercariae are considered in this paper. Three new species of Xiphidiocercariae are described in detail and a fourth cercaria from this group is recorded from Britain for the first time. The further development of one of these cercariae has been considered. A new species of Microcercous cercariae is also described in detail.

During a three year study of the larval trematodes of Llangorse Lake, South Wales, twenty-one species of cercariae have been encountered. The present paper deals with four cercariae of the Gymnocephalous group. Two new species of Agilis cercariae are described in detail; Cercaria Sphaeridiotrema globulus is recorded from Britain for the first time and the occurrence of Cercaria lophocerca noted

1. A new species of Oxysomatium (O. minutum) is described from a frog Rana ptychadena mascareniensis.

2. The crested chameleon (C.? cristatus) and Bufo supercilioris are reported as new species of hosts recorded for Africana africana (Gendre, 1909) Travassos, 1920.

3. Strongyluris brevicandata Müller, 1894 and Thelandros sp. are reported from Agama agama agama.

4. Amplicaecum involutum (Gedoelst, 1916) Yorke and Maplestone, 1926 is redescribed from Chamaeleon (?) cristatus which is regarded as a new host record and A. pesteri n.sp. from Bufo superciloris is described to be the smallest species of this genus.

In the First Report of the W. H. O. Expert Committee on Bilharziasis (1953) it was stated: “Infection with Schistosoma is often well tolerated and without clinical signs, however this relative benignity appears to vary considerably from country to country, without the cause of these variations being as yet thoroughly understood”. This statement refers to the relative absence of serious manifestations of schistosomiasis as has been reported by various investigators working in Africa, e.g. Ramsay (1934) working in Nigeria, Dixon (1934) and Fisher (1934) in the Congo, Gelfand (1950) in Southern Rhodesia, Mackey (1953) in Tanganyika, Manson-Bahr (1958) in Kenya and Nelson (1959) in Uganda as compared with the situation reported in Egypt and South America.

Yeh Liang-Sheng and Fotedar (1958) reviewed the genus Astiotrema Looss, 1900 and considered A. reniferum, A. impletum, A. odhneri and A. monticelli as the only valid species of the genus. They transferred A. emydis Esjmont, 1930 to Leptophallus Lühe, 1909 without giving any reason. However, recently Grabda-Kazubska (1961) has rightly revalidated A. emydis. Since the revision of the genus by Yeh Liang-Sheng and Fotedar (1958), three more species have been added. They are A. geomydia Siddiqui, 1958, A.sudanensis Khalil, 1959, and A. trituri Grabda, 1959.