Material examined. A male and a female from Trichoglossus novae-hollandiae in a bird store in San Francisco. This is one of the type host species and the specimens agree entirely with Harrison's description, making the determination quite positive.

The material for this paper was obtained from snakes, Tropidonotus piscator, caught near water pools in Kamayut, Rangoon. Six were dissected, two of which yielded about nine specimens of Encydometra bolognensis (Baer, 1924) from the oesophagus on each occasion. One of them had only one adult and one immature specimen of Xenopharynx piscator n.sp. in its gall-bladder.bladder. Two others had their intestines infected with numerous specimens of Acanthochasmus burminis n.sp. Specimens of Encydometra bolognensis were obtained from grass-snakes, Tropidonotus natrix, by Baylis and Cannon and Baer on previous occasions. A different species of Xenopharynx, namely X. solus Nicoll, 1912, was obtained by Khalil in 1923 and by Nicoll in 1912 from the gall-bladders of Indian cobras, Naja bungarus and Naja tripudians respectively. It appears, therefore, that the types of the genus Xenopharynx are common parasites of the gall-bladders of the Ophidia in the Indian region. Species of Acanthochasmus have been previously recorded from reptiles as well as fishes.

In spite of the fact that frogs form a common subject of biological examination and experiment it is curious that, in this country, there have been few reports on the helminth parasites with which they are so frequently infected. We owe practically all our knowledge of the Trematode parasites of amphibians to continental zoologists. The early researches of von Frölich (1789–1802) and Rudolphi (1809) followed, a hundred years later, by those of von Linstow (1877–1890) and Looss (1894–1901), are responsible for the greater part of the existing information. Amongst others who have devoted some attention to the subject may be mentioned the names of Dujardin (1845), Diesing (1836–1858), Gastaldi (1854) and Olsson (1876).

Although, in the early part of the nineteenth century, a considerable amount of work on larval trematodes was done on the continent by von Siebold (1835), de Fillippi (1855) and La Valette (1855), so far as I know, no similar work was undertaken in this country. It was not until 1880, when a great controversy raged round the intermediate host of the liver fluke, that any interest was aroused. This culminated in 1883 with the publication, by Thomas, of the life history. Thomas also discovered that Limnaea peregra was infected with cercariae different from those of the liver fluke. Since that time the interest has lapsed, and, excluding a description of two cercariae by Hesse (1923), I do not know of any published records of work on freshwater larval trematodes of this country. On the other hand, work on the continent and in America has increased, and although our knowledge of the life histories of trematodes is still in its infancy, a considerable number of continental larval forms have been found and described. However, Lebour (1905) commenced a study of marine larval trematodes and together with Nicoll (1906) attempted to establish life histories.

Our knowledge regarding the biology of Hippoboscidae is but fragmentary. Leuckart (1858) and Pratt (1900) have described the embryology of Melophagus ovinus L. Austen (1903), who described the puparium of Hippobosca maculata Leach, found that the females soon starve when removed from their host. Austen continues: “It is believed that the females of the genus Hippobosca deposit their larvae on the ground, but it is not definitely known, whether they bury them or merely place them on the surface. Several pupae of H. maculata have been found in the calf sheds of the King Institute, but it is not clear, as to whether they were intentionally or accidentally deposited there.” Theobald (1908), on the contrary, asserts that female H. camelina and H. maculata attach their pupae to their host's hair. Massonat (1909) relates that the pupation period of H. equina varies with the temperature.

Early in 1925 I received from Mr E. Jacobson a mite taken in 1918 from the Passalid beetle Gnaphalocnemis (Eriocnemis) burmeisteri Kaup. on the east coast of Sumatra. It clearly belonged to the genus Megisthanus, and was apparently new. I had described and figured it before I showed it to Mr Stanley Hirst of the British Museum (Natural History), South Kensington. He informed me that he had received both sexes of what he believed to be the same mite, and most kindly offered to hand over to me the material to complete my account of the new species. By the courtesy of Sir Sidney Harmer he was permitted to do this, and I have therefore been able to examine, as regards external features, four female and three male specimens.

Broadly oval, 5·8 × 3·9 mm., slightly broader at the posterior third; rounded in front, the posterior border more flattened. Integument mammillate and with dorsal depressions and discs, and ventral grooves strongly recalling O. coriaceus (see Fig. 1). Numerous short white hairs scattered over the integument, and notably a ring of close-set clavate hairs round the base of each trochanter. Eyes absent. The half-gorged ♂ measures 6 × 4 mm.

Habitat and Record. Six females, three of which were adult and of equal size and the rest small and imperfect, of a new species of Naobranchia, easily recognisable as being the only one as yet described in which the cephalothorax is definitely shorter than the trunk, were taken by L. Harrison Matthews on 7 viii. 1923 during his visit to Brazil, at Praia de Icarahy, Rio de Janeiro, on the gills of the Diodontid globe-fish Chilomycterus spinosus.

Several visitors to the Molteno Institute having expressed a wish for a description of certain cases in our Museum, and believing that the types of cases I have devised, with the aid of a local carpenter, may appeal to others desiring inexpensive cases or stands for similar purposes, I herewith append an account of them. The cases are intended for the reception of specimens that are not frequently shifted about.

In a paper published in July 1924, Professor Brumpt has done me good service by criticising certain views of mine on the epidemiology of human trypanosomiasis (Brumpt, 1924).

Some two years ago a proposal was put forward by Wenyon (1923) to change the name of one of the well-known coccidial parasites of man—the parasite which, in my revision of the group (1919), I called Isospora hominis (Rivolta). for various reasons Wenyon concluded that there must really be two species of Isospora in man—not one, as I had assumed—and he proposed to transfer my amended name I. hominis to another organism, whose existence he deduced from the literature and from his own observations on the Coccidia of cats and dogs: but as this would leave the species which I had called “I. hominis” without a name, he proposed to rename it “Isospora belli”.

The present paper is a further instalment of the Reports on the Molteno Institute collection, of which Parts I–III, dealing with the Ascaridae, Heterakidae, Oxyuridae, Camallanidae, etc., were published in this Journal by Dr H. A. Baylis in 1923. The history of the collection has been dealt with by that writer, and the following report on the Trichostrongylidae and Strongylidae is presented in as nearly as possible the same form as that of the preceding parts, consisting of a list of determinations of the material, together with notes on the less well-known forms and full descriptions of the new species. As in Parts I–III, the numbers attached to each set of specimens are the serial numbers given to the original tubes at the Molteno Institute.

1. Fourteen species of larval trematodes are described from South African material, of which thirteen are new to science.

2. These forms are described and their relationship to previously described cercariae and to adult flukes is discussed.

3. The cercariae of the human blood flukes of South Africa are brought up for detailed consideration. A restudy of the material in the writer's possession, including the original experimental material of Schistosoma mansoni from Venezuela, is presented.

4. The writer restates his original thesis:

The essential differentiating features of the apharyngeal fork-tailed cercariae consist in the number and microchemical reactions of the secretory cells. These structures can be studied and differentiated from well-preserved material as well as from fresh material.

5. Isidora (Physopsis) africana from Natal is known to harbour three species of mammalian schistosome larvae, of which (a) one, originally diagnosed by the writer as the “Cercaria of Schistosoma haematobium,” is found on re-examination to correspond to the larva which Blacklock and Thompson have found experimentally to be this species; (b) a second species corresponds exactly with that known experimentally to be the cercaria of Schistosoma mansoni in Venezuela; while (c) a third (C. octadena) is probably that of Schistosoma bovis, which is known to be présent in Natal.

6. A table is presented which embodies the important diagnostic features of the three human blood-fluke cercariae.

7. The systematic position of the thirty-eight species of larval trematodes described from Cawston's collections and their host relationships are summarised.

Although our knowledge of Filariae parasitic in animals is continually increasing, the main source of information concerning this group remains still confined to the important monographs by Molin (1858) and Stossich (1898). Molin's descriptions of worms are, however, often so incomplete that in using them as a basis of classification Diesing failed in his attempt to subdivide the genus Filaria, whilst Stossich's descriptions are scarcely better than those of Molin. Stiles has already pointed out the absence of clear and definite characters for the subgenus Filaria of which Filaria martis Gmelin is the type-species. Before any new division of the genus Filaria is proposed the writer thinks it is advisable to re-investigate the already known species and to re-describe them more carefully, laying special stress on such characters as the structure of the female genital organs and the structure of the microfilariae. The knowledge of Filariae parasitic in animals will be of great help in identification of worms parasitic in man.