A new species of larval trematode, C. projecta, infects Helisoma antrosa. The very small distome cercaria is ontogenetically young, showing no traces of reproductive anlagen even after excystment. It belongs to the cystophorous cercariae, and has a vesicular tail into which the body of the cercaria withdraws when mature. In this encysted state the cercaria is expelled from the snail and awaits ingestion by the next host. The redia is a large, elongate sac, without “feet,” possessing a small pharynx, short intestine and an excretory system consisting of a longitudinal channel and at least sixty flame cells on each side of the body. Excystment is caused by mechanical pressure which releases a force within the cyst, which projects the cercaria very rapidly through a long cuticular tube, the excretory projection, to a considerable distance away from the cyst. Various complex appendages of the tail vesicle along with parts of the excretory system play a large part in this process of excystment. As postulated, the purpose of this type of excystment is to throw the larva away from its cyst, to prevent it from being regurgitated from the body with the empty cyst.

In February 1928 I obtained from a ♂ Scyllium canicula, taken at Plymouth, a ♀ Lernaeopoda scyllicola bearing a younger and better preserved male than any I had hitherto observed. It is the first time in this genus that a male has been found anywhere other than on the female's shoulder, namely on one of the abdominal appendages, and the male was probably alive at the moment of fixation. The heads of the sexes point in opposite directions so that in Fig. 1 the abdominal appendage is “upside down,” and the genital process of the male is near a vulva of the female which is however fertilised since it bears egg-strings. I am now fortunate in having the kind services of Miss E. C. Humphreys to illustrate this male which is not shrunk into its carapace and desire that Figs 1. and 2 shall supersede my figures of 1918. The near second maxilla has been omitted to show the method of attachment of the male.

A description of Zalophotrema hepaticum is presented. Study of this species and review of the literature show that the genera assigned to the two families, Fasciolopsidae and Campulidae, may be included in a single family. Furthermore, since Fasciola is the nomenclatorial type of the family to which it belongs, the rules of nomenclature do not permit the substitution of the name Fasciolopsidae for Fasciolidae. Consequently the family Fasciolidae is restored with three sub-families, Fasciolinae, Fasciolopsinae, and Campulinae. A new genus, Synthesium, is erected to contain Distomum tursionis Marchi.

Of this Cestode I possess about a dozen adult specimens from one bird and nearly two dozen young specimens from another bird, preserved in the collection of the Wellcome Bureau and originally obtained, I believe, by Dr L. Sambon from the London Zoological Gardens. It is probably allied to, though certainly not identical with, the Ascometra vestita of Cholodkovsky (1912) obtained from the same host, viz. Houbara macqueeni. I have no information as to the locality from which the hosts were obtained in the present case. I shall describe the anatomy of this worm prior to discussing its systematic position.

The question of the mode of transmission of the Trichomonas of man from one host to another is of particular interest because no authentic encysted stage is known.

Many workers have attempted to infect “clean” animals by the mouth with active trichomonads from a variety of hosts, either from cultures or directly from faeces. The results are conflicting. Thus Escomel (1913) fed faeces containing Trichomonas intestinalis (= T. hominis) from a human case of dysentery to a rabbit, a guinea-pig, a cat, and a dog, and obtained a positive result in the dog. He does not, however, state that he examined his animals, to find whether they had any similar natural infections, before performing his experiments. Boyd (1919) fed a culture of Trichomonas intestinalis (= T. hominis), mixed with milk, to a white rat and infected it. He had previously examined this rat and one used as a control and found them to be free from this flagellate. He was, himself, uncertain whether the infection was due to the free flagellates or their “cysts“ which he says were present in the culture. The cysts figured by him (Plate XI, figs. 7–17) appear to be rounded-up and degenerating trichomonads. Pringault (1920) fed Trichomonas intestinalis (= T. hominis) to a cat, a guinea-pig, a rabbit, and a white rat, without establishing an infection in any one of them.

In the Final Report of the League of Nations International Commission on Human Trypanosomiasis, published in 1928, an account was given of experiments on the transmissibility of T. gambiense by G. palpalis. These experiments, though admittedly incomplete, suggested certain conclusions, the chief of these being that prolonged sojourn of T. gambiense in an individual, whether man or animal, in which the trypanosome produces a slowly progressive illness, tends to reduce and eventually to abolish the transmissibility of the strain by tsetse.

Pp. 183–4. The specific names of the parasite and the host should be transposed.

P. 277. Legend to Fig. 5, for dubius, read bicaudatus.

Three lines from bottom of page, for ♂♂, read ♀♀.

Habitat and Record. By the courtesy of G. Evelyn Hutchinson of Yale University, I have received and examined a new species of Lernaea collected by him on 7. iv. 1928 on a small Barbus, which had lost all its scales and was too young for specific identification, from an alkaline pan in the Transvaal, S. Africa. For the purpose of comparison reference will be made to L. elegans described by me, Parasitology, 1925, 17, 246.

1. In general there is a correlation between the life-history of Gonospora arenicolae and the sexual cycle of its host, Arenicola ecaudata, similar to that between G. varia and Audouinia tentaculata.

2. In the species under consideration the correlation is not so definite and the life-history of a generation of parasites does not necessarily coincide with a sexual cycle of the host. This is complicated by the double annual spawning of the host.

3. The formation of sporocysts is simultaneous with the sexual maturity of the worm.

4. It is suggested that, as in Audouinia, a secretion produced by the gonads stimulates the development of the gregarine.

5. The ejection of the sporocysts with the gametes was observed.

6. It is suggested that phagocytosis may be the cause of the rupture of the gametocysts in this species.

A short historical account is given of the writings on flea larvae since the seventeenth century. The larvae have been known since Leeuwenhoek tried to breed them in 1683.

The life-history of Ceratophyllus wickhami is described. The fleas were bred in the laboratory on a grey squirrel. Three larval instars occur, and the life-history occupies, on an average, 6 weeks under experimental conditions.

The external anatomy of the third instar larva of C. wickhami is described. The mouth parts are generalised and suggest the condition of a primitive insect. The tracheal system is composed of a double longitudinal trunk on each side, with spiracles on the prothorax, metathorax and first eight abdominal segments.

The first and second instar of C. wickhami are similar to the third instar larvae, except in size and the presence of a hatching spine in the first stage.

The larva of Ceratophyllus fasciatus is mentioned. The importance of the species lies in the presence of completely separated galea and lacinia.

Larvae of Xenopsylla cheopis and X. astia are briefly described. The larvae of the two species are practically identical except for the shape of the mandibles.

Originally containing only four genera, this family of recent years has been increased by the addition of twelve more and has further been subdivided by Hunter (1927, 1929) into four sub-families: Caryophyllaeinae, Lytocestinae, Pseudolytocestinae, Wenyoninae. Of these, the Lytocestinae and Pseudolytoeestinae have vitellaria either wholly or partly in the cortical parenchyma and differ from each other only in the degree to which these are cortical; a difference hardly of sub-family rank, which should consist of characters of absolute not relative value: the Caryophyllaeinae and Wenyoninae, with vitellaria wholly medullary, differ from each other in the position of the genital pore and the absence of uterine glands, differences again not of sub-family rank. There remain therefore two well-marked sub-families, the Caryophyllaeinae and the Lytocestinae, the differences between which are given in the following table.

Material. On 28. V. 1928 two females of Brachiella merluccii Bassett-Smith, 1896 were taken by the author from the tips of the gill-rakers of a single Merluccisu vulgaris at Plymouth. One of these was accompanied by a male upon the cephalothorax. The female is generally well known, but there is no complete account of the appendages of the male.

The disease “Heart-water” of sheep, cattle and goats has been recognised in South Africa for upwards of 70 years, and as long ago as 1902 Lounsbury demonstrated the part played by the common bont-tick, Amblyomma hebraeum Koch 1844, in its transmission. The virus of the disease does not pass through the egg of the tick, but a tick infected in the larval or the nymphal stages is capable of transmitting the infection when feeding as a nymph or adult respectively. Further, according to Lounsbury, a tick infected as a larva may feed upon an insusceptible host during the nymphal stage, and still remain infective until the final feed as an adult.

Since the description by Linnaeus in 1758 of the very irritating patatta-mite (“patatta-luis”) of Surinam under the name Acarus batatas, this parasite has often been mentioned in the literature, but seldom have attempts been made to learn more about it. Furthermore, many important data have been omitted by authors in their writings, so that it seems desirable to summarise what is known of this mite.

I have examined (a) alcoholic and microscopic specimens of Birula's type-material of O. papillipes preserved in the Zoological Museum of the Academy of Sciences, Leningrad, and (b) hundreds of living ticks from different localities in Turkestan which I determined as O. papillipes. The larger number (b) were chiefly supplied by Dr I. A. Moskwin, who, in my laboratory and at the Infectious Diseases Clinic of our Academy, demonstrated that the spirochaete of Turkestan, relapsing fever, is transmitted by this tick.

The advantages and difficulties of various methods employed in the study of larval trematodes are discussed. The desirability of using living specimens rather than fixed material and of studying mature, normally emerged cercariae rather than those obtained by crushing the host is noted. Intra-vitam staining with neutral red is recommended to demonstrate the form and reaction of the secretory granules in gland cells. Knowledge of the details of the excretory system is of major importance in both theoretical and experimental work.