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.

In 1925 I described a new species of Monopylidium, M. chandleri, proposed a new subgenus Macracanthus for this and two related species, and proposed a new genus Southwellia for the species Monopylidium gallinarum Southwell 1921. Dr M. C. Hall has very kindly drawn my attention to certain errors and omissions in this paper which are herein corrected.

During the past few months we have collected a considerable amount of information relating to the value of pH. as affecting the distribution of the three species of Limnaea commonly found in North Wales. Tables I and II show that L. truncatula occurs over a range of pH. 6·0 to 8·6, and L. peregra 5·8 to 8·8; L. palustris was recorded from 7·4 to 8·0 (but only three of the readings included this species).

The acephaline gregarine, Gonospora varia Léger, from the coelomic cavity of the Polychaete worm Audouinia (Cirratulus) tentaculatus (Montagu) exhibits an interesting phenomenon, in which the life-history of the parasite is closely bound up with the sexual cycle of the host. It is characteristic of the acephaline gregarines that they are, for the most part, inhabitants of the coelom, and, as a consequence, frequently live in very close association with, if not actually parasitic on, the reproductive cells themselves. The familiar Monocystis from the seminal vesicles of the earthworm is an example which is at once called to mind. So, in the case of gregarines such as Gonospora, it is a common feature for them to spend the greater part of their existence free in the body cavity among the host's genital products. Naturally, they are reliant on the host's method of expulsion of the ova or spermatozoa for the dispersal of their spores. We therefore find that the periodic annual spawning of the worm is accompanied by a corresponding periodicity in the life-history of the parasites, which probably results in the reproductive bodies of both parasites and host being expelled together. In this point there seems to be a somewhat greater degree of specialisation than in Monocystis, where it is generally accepted that the spores are shed only on the death of the earthworm, either naturally or as the prey of some bird.

1. Egg masses of Limnaea truncatula collected in March 1925 were isolated and hatched in the Laboratory. The average number of ova per mass (for 20) proved to be 9·75.

2. The hatching period lasted 12 to 26 days, with an average of 20–21 days (for the Spring generation).

3. On hatching, young snails were isolated, reared, and again oviposited during the first week of July. Ova from these snails again hatched during the first week of August.

4. It is thus shown that L. truncatula is self fertile; that oviposition can commence at a shell altitude of 4 to 4·5 mm.

5. Further data on growth-rates were obtained, showing that two (and probably three) generations occur between March and October.

In a note which I contributed in 1918 to Special Report, No. 19 of the Medical Research Council, I attempted to show that the “correct” generic name of the spirochaete of syphilis—according to the Rules of Nomenclature—is Spironema Vuillemin, 1905. The premisses from which this conclusion was drawn were briefly set out in the publication cited, and need not be repeated here: but my argument—put very shortly—was that, since the Spirochaetes are Bacteria, and not Protozoa, their nomenclature must be determined by the Botanical Rules, not those of Zoology; and that of the three generic names proposed for the spirochaete of syphilis in 1905, Spironema has priority, and must therefore be accepted. (Spironema was proposed by Vuillemin in June, Treponema by Schaudinn in October, and Microspironema by Stiles and Pfender in December, 1905.)

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.

Family Diagnosis. Copepoda parasitic dorsally on Polynoid Worms.

Female with body divided into cephalothorax (head and neck) and trunk. No appendages articulated or otherwise on head or neck. No traces of segmentation. No mouth nor alimentary canal. Cuticle thin. Head and neck buried in the tissues of the host; the head converted into a voluminous organ whose only function is to absorb nutritive materials by endosmosis through expansions or rootlets. Head and neck at right angles to the middle of the trunk. A chitinous ring is usually present at the base of the neck at its insertion on the trunk. Genital apertures wide, the pyriform eggstrings issuing therefrom.

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).

Since the publication of the original paper by Audouin and Milne-Edwards (1826, Ann. Sci. Nat. vol. IX), no investigator appears to have thoroughly examined Nicothoe astaci. It therefore seemed to me desirable that this Copepod should be reinvestigated by modern methods in respect to the morphology of its appendages.

The systematic position of Nematodes is an old standing problem which has already received much attention from zoologists. The conclusions at which they have arrived are however very discordant and the most widely separated orders of Metazoa have been claimed as near relatives of Nematodes. This great divergence of opinion has not abated the general interest in the problem, but, on the contrary, has had a greatly stimulating effect as was shown recently at the British Association for the Advancement of Science (1923) in a discussion on the affinities of Nematodes, opened by Prof. Hickson and supported by Prof. Goodrich and Dr Baylis. The results of this discussion were soon afterwards incorporated by Dr Baylis in a very interesting paper containing a complete review of the problem as well as a statement of the author's own views.

Dans un travail publié précédemment dans cette revue, nous avons montré que la concentration moléculaire du liquids cœlomique d'Ascaris megalocephala était voisine de Δ = − 0°, 63 avec de petites variations; d'après nos expériences, l'Ascaris était susceptible d'une régulation osmotique; il augmente de poids dans une solution hypotonique par rapport à son liquide; il y a pénétration d'eau; dans une solution hypertonique il diminue de poids (départ d'eau).

The material for this paper was obtained partly at Allahabad and partly at Nagpur from Rana tigrina. In those dissected at Nagpur Centrovitus pentadelphi n.g., n.sp., was found in the duodenum and in the intestine and but once in the oesophagus. This species was also found in the duodenum and intestines of the frogs at Allahabad, but there in addition was obtained once from the stomach and once from the rectum. Ganeo glottoides (Klein, 1905) was found but twice in the intestines of frogs at Allahabad.

The term “Myiasis” is generally used to indicate the presence of Dipterous larvae in the living body of man or other animals. “ The form of Myiasis most commonly met with in the United Kingdom,” writes Austen (1912), “is that of the alimentary canal, as the result of which living larvae or pupae, greatly to the distress and alarm of the patient, are discharged from the bowel. Cases of Myiasis of the nasal passages and frontal sinuses the external auditory meatus, the subcutaneous tissue, and the urinary passages are apparently of quite exceptional occurrence in the British Islands.” The following pages deal with three hitherto unrecorded cases, two of urethral and one of intestinal Myiasis.

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.

The method devised by Boeck and Drbohlav for the cultivation of E. histolytica has been successfully used for cultivating this species and various other entozoic amoebae of man and monkeys.

Various modifications of the original technique have been tried, and several improvements are here described. Among these are methods of cultivation (involving the addition of solid rice-starch to the medium) whereby (1) more luxuriant and prolonged growth of the amoebae, and (2) all stages—including encystation and excystation—in the life-cycle of E. histolytica and other species can be obtained in vitro.

Methods by which cultures of entozoic amoebae can be initiated from encysted forms have been discovered and are also described, and some indications are given for the isolation of pure strains from mixed cultures.

The influence of the accompanying bacterial flora upon the various amoebae cultivated has been studied, and is briefly discussed in the light of certain experimental findings.

Loss of infectivity to kittens has been observed in E. histolytica as an apparent result of cultivation in media containing solid starch.

In a collection of the early stages of Simuliidae, made by Mr F. W. Edwards, in the summer of 1923, from the rapids above Tännforsen waterfalls, Sweden, there are representatives of 11 species of Simulium: larvae and pupae of S. venustum Say and S. tredecimatum Edw., larvae of S. morsitans Edw. and S. reptans var. galeratum Edw., pupae of S. tuberosum Lundstr., larvae and pupae of S. pusillum and pupae of S. pallipes Fries and S. lyra Lundstr., besides pupae of three other indeterminable species. In a previous paper I have already described, in detail, the early stages of the first five species, and in the present paper I deal for the first time with the remaining six species and the early stages of S.ferruginum Wahlgr. The pupae of S. pusillum Fries, S. pallipes and S. lyra were identified by Mr Edwards, by dissecting out the male genitalia, but those of the remaining three species, herein described as species I–III, are indeterminable owing to their immaturity. It seems inadvisable to give the pupae new specific names as further investigation may prove that they belong to well-known Continental species.

Though the structure of the head and the proboscis of Hippoboscidae has been studied by many observers, their descriptions are in some respects incomplete. When, therefore, living specimens of Lynchia maura Bigot were brought to the Wellcome Bureau by Dr W. N. F. Woodland from Algiers and these were successfully bred on pigeons in captivity, I availed myself of the opportunity to reinvestigate their structure. In addition, Melophagus ovinus L. and many other forms belongs to the family were examined with special reference to the structure of the head and mouth parts.

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.

Since the publication of a paper by Bassett-Smith (1896, Journ. Mar. Biol. Assoc. n.s. IV. 155) a considerable number of new species and other species of parasitic Copepoda has been taken at Plymouth. Bassett-Smith's work forms the basis of this list, but some species are now assigned to other genera, or degraded as synonyms, while in some cases the names of genera are changed owing to preoccupation. Additions have been made by the collections of L. Harrison Matthews and myself.