The larval trematodes described in this paper were obtained from fresh-water molluscs collected from Rostherne Mere and a pond near Ashley, both in Cheshire. Rostherne Mere is a large sheet of water and carries an extensive fauna, vertebrate and invertebrate. The molluscs were collected from various fixed positions in the littoral region, and this method has confirmed previous observations (unpublished) in other stretches of fresh-water on the variation in the distribution and localisation of infected molluscs. How far this may be related to movements of the final host or to physical factors affecting the migration of the molluscs is at present uncertain; further observations are being made in an attempt to elucidate this problem. The molluscs were isolated in the laboratory in 3 × 1 glass specimen tubes, when the infected specimens were easily seen by the swarming of the cercariae, and all observations (including measurements) were made on these living, fully developed cercariae. Infected snails were later crushed in physiologically normal saline in order to obtain living sporocysts or rediae for examination. Measurements are, of necessity, only approximate owing to the slight pressure exerted by the weight of the cover-glass and the great powers of contraction and extension of these larval forms. Neutral red was used as an intra vitam stain; it also inhibits movement. Of the five species described four are new, the fifth, for which a further stage in the life history is described, being little known and not previously recorded for this country.

The following description is based upon a single fully engorged female collected under a stone at Kamieskroon, Little Namaqualand, by Dr R. F. Lawrence in October 1930. Dr Lawrence informs me that rock-rabbits were probably the commonest animals about the hill where he found it, but the host of the tick may be a bird.

In the Final Report of the League of Nations International Commission on Sleeping Sickness (1928) certain tentative conclusions were expressed about the behaviour of T. gambiense, recently isolated from man, in the blood of monkeys and of certain domestic ruminants. These conclusions, which were intended primarily to serve as a basis for further researches, were set forth in the Summary of Part I of that Report, and read as follows:

The new species herein described was found in three species of monkey at the Moscow Zoopark, the animals having been imported via Germany.

Record and Habitat. I am indebted to Dr Theodore Monod of Paris for his kindness in sending me four female specimens of Basanistes huchonis (Schrank) which, according to him, is common on Salmo hucho on the inner side of the operculum, in the rivers of Continental Europe. In 1928, Parasitology, 20, 183, I gave an account (in which by an error the specific names of the host and parasite were unfortunately interchanged) of the external features, with figure, from the single specimen in the British Museum, which it is unnecessary to repeat here. As the Museum specimen lacks a bulla and the appendages of Basanistes, owing to its apparent rarity, have not been adequately described, I append the following account. The male is still unknown.

1. The red-cell adhesion phenomenon in trypanosomiasis of man and other animals, first described by Duke and Wallace (1930) and shown by these authors to be due to the presence in the blood of the infected animal of a sub-stance (adhesin) which appears during the course of an infection, has been investigated further. Several strains of T. rhodesiense and T. gambiense have been used for this study.

2. Red-cell adhesion of this nature has been obtained with the red blood cells of primates only, thus confirming the earlier finding.

3. No relationship appears to exist between red-cell adhesion and isohaemagglutination, or other types of haemagglutination. The removal, by absorption, of the α and β isohaemagglutinins from a human adhesin serum of blood group O, or the removal from a monkey adhesin serum of agglutinins for baboon, rabbit and guinea-pig red cells does not lead to the removal of the adhesin.

4. Centrifuging, per se, does not destroy to any appreciable extent the power of trypanosomes to adhere to red cells.

5. Trypanosomes which have been freed from plasma by centrifuging and subsequent washing with citrate-Ringer-glucose solution give good adhesion with human or monkey red cells when a fresh adhesin serum or plasma is used. Little or no adhesion is obtained with these washed trypanosomes however, if the adhesin serum is very old or if it has been previously filtered through a Berkefeld filter candle or if the adhesin serum or plasma has been heated at 56° C. for 30 minutes.

6. From this and other evidence the conclusion is reached that in addition to the red cells, trypanosomes and the adhesin some other factor (designated the “X” factor) is necessary for red-cell adhesion.

7. This “X” factor is present in the serum or plasma of humans, monkeys, baboons, rabbits and guinea-pigs and has properties similar to those of complement. It is removed, as is most of the haemolytic complement, when the serum is filtered through a Berkefeld filter, it is destroyed by heating at 56° C. for 30 minutes, and, like haemolytic complement, it is inactivated when the serum is subjected to the action of dilute ammonia for about 1½ hours. Filtration, heating at 56° C. for 30 minutes and dilute ammonia appear to have no significant destructive action on the adhesin.

8. The requirements for this red-cell adhesion phenomenon are (a) the red cells of a primate, (b) an adhesin, which is probably an antibody-like sub-stance produced during infection with trypanosomes, (c) trypanosomes of a strain related to that which gave rise to the formation of the adhesin, and (d) a complement-like component (“X” factor) present in the plasma and serum of most, if not all, normal animals.

I am indebted to my friends, Messrs M. A. Moghe, of the College of Science, Nagpur, and W. V. Nene, Officer-in-charge of the Time-Ball Observatory, Rangoon, for the material described in this paper. The trematodes were obtained by the former from the duodenum of Uromastix hardwickii (the spinytailed lizard) brought to Nagpur from Northern India, and Mr Nene gave me the tortoise, Batagur baska, which was found to be heavily parasitised with nematodes, along with two flukes. In both instances the trematodes proved new to science.

An account is given of the life cycle and morphology of T. grayi in the crocodile (Crocodilus niloticus) and in the tsetse-fly (Glossina palpalis). The immunological relations of this trypanosome to its hosts and its affinities to other species are also dealt with.

T. grayi belongs to the group of trypanosomes developing in the posteriorstation of the invertebrate host and transmitted by the contaminative method (“lewisi group”).

T. grayi occurs in very small numbers in the crocodile and is concentrated chiefly in the peripheral circulation of the skin (about 200 parasites per 1 c.c. of blood). It is one of the largest trypanosomes, the blood forms measuring up to 91μ

When fed on an infected crocodile the tsetse-fiy takes up not more than about six trypanosomes. These commence their development in the mid-gut, giving rise to crithidial and trypanosome forms, and later extend to the hind-gut where their evolution is completed and the infective metacyclic trypanosomes are produced. These, when voided with the faeces, serve to infect the crocodile per os.

Since the incubation period of T. grayi in the crocodile is about four days, this is the time required for the small metacyclic trypanosomes to develop into the large blood forms.

The distribution of T. grayi in the gut of the fly in the course of its development is determined by the presence of the peritrophic membrane and involves three successive waves of migration in opposite directions: (1) From the intraperitrophic space backwards, into the colon, thence (2) forwards into the extraperitrophic space up to and including the mid-gut; and finally (3) they again migrate backwards, to the hind-gut. (Diagrams of the life cycle and distribution of T. grayi in Glossina are given in Text-figs. 2 and 3.)

Evidence is produced to show that the so-called “cysts” of T. grayi described by previour authors are really artifacts.

Apparently the majority of crocodiles in Victoria Nyanza harbour T. grayi. The trypanosome has no harmful efleet upon the crocodile and it was proved that the infection can persist for more than two years.

The crocodile appears to possess a natural partial or tolerance immunity against T. grayi, which does not protect it from invasion by the parasite, but maintains its numbers at a constantly low level.

The infection rate in the experimental tsetse-ffies is very high (average 61 per cent.) in the early days of infection, but later f ails to an average of 17·3 per cent. The majority of the flies, originally fully susceptible to infection, appear to acquire an immunity after the fifth day.

The average degree of infection in “wild” flies is 11·2 per cent. This compares closely with that in the experimental flies. Hence it is inferred that the majority of these flies had fed in nature on infected crocodiles.

T. grayi is closely allied to trypanosomes of the “lewisi group” and to some of the trypanosomes of land reptiles and amphibia. On the strength of the clifterence existing between these two groups of trypanosomes, some modification in the accepted classification of these species is introduced.

A name, T. theodori sp.n., is proposed for the goat trypanosome described by Theodor (1928).

1. Studies were made on the morphology, with special emphasis on the taxonomic characters, of 220 mature male and female Ascaridia lineata (Schneider) from chickens at Manhattan, Kansas, U.S.A., and Cambridge, England.

2. Eggs arising in the anterior ovary pass into the posterior uterus; similarly, eggs from the posterior ovary pass into the anterior uterus.

3. In young females eggs may be fertilised at any place in the uteri; in adults, fertilisation occurs near the distal ends of the uteri.

4. With the aid of a micromanipulator, a small structure in one pole of the mature egg, previously decribed as an opening, an opercular plug in the shell, or as an internal thickening of the shell, was found to be a solid, conical appendage of the vitelline membrane, free from the shell.

5. Fertilised eggs develop to the coiled embryo (infective) stage in 16 days when incubated in water at 30° C.; in 1 mm. of water at 33° C., they become infective in 10 days.

6. Water cultures of fertile eggs do not develop when kept at constant temperatures of 0° C., or of 10° C.; at 15° C., development proceeds.

7. Constant refrigeration of fertile eggs in water cultures for 1 month at 0° C. so lower the vitality that, on being incubated subsequently at 30° C., they divide slowly and soon die; keeping the eggs at 10° C. for 1 month has no deleterious effect on them when incubated subsequently at 30° C.

8. In hatching, the embryo may escape from any part of the egg shell, either in the duodenum of the host, or in water cultures; newly hatched larvae swallowed by the chicken seldom become established; infestation normally result from the ingestion of embryonated eggs.

9. The habitat of A. lineata is the duodenum, especially the portion which is a few centimetres posterior to the entrance of the bile ducts; determination of hydrogen-ion concentrations showed that the nematodes live in nearly neutral media (av. 6·7).

10. Penetration of the duodenal mucosa by larvae 10–17 days old is frequent in young chickens; occasionally, a larva goes on through the intestinal wall to the liver and lungs, but ordinarily, after the 17th day the young worms withdraw from the mucosa into the lumen of the intestine.

11. Young A. lineata grew to maturity in 50 days in chickens parasitised when about a month old; in six 8-day periods following hatching of the larvae, the average daily growth in length per period was about 0·12 mm. in the first period, 0·75 mm. in the second, 1·5 mm. in the third, fourth, and fifth periods, and 3mm. in the sixth period.

12. At least three moults occur before the adult from of the nematode is developed. Important morphological changes associated with the moults include: after first moult, presence of pre-anal swelling (males), and of anal prominence in both sexes; after second moult, lips with oral papillae and dentigerous ridges, projecting Iateral folds (alae) present in newly hatched larvae replaced by non-projecting lateral lines, females with vulva and shorter tail proportionately, and males with pre-anal sucker and three pairs of caudal papillae; after third moult, external characters similar to those of the adult A. lineata.

On comparing the figures it will be observed that all the specific characters of Tetrophthalmus titan (A in all figures) closely resemble those of T. subtitan (B in all figures), and that these two species constitute one group; also that the specific characters of T. africanus (C in all figures) closely resemble those of T. australis (D in all figures), and that these species belong to another group, which must also include T. chilensis.

Judged by their parasites, the Ethiopian pelican, Neopelecanus rufescens, is more closely allied to both the Australian pelican, Catoptropelecanus conspicilatus, and the South American species, Pelecanus thagus, than it is to either Pelecanus onocrotalus or Metapelecanus roseus, both of which also occur in the Ethiopian region. Moreover, if the parasites throw any light on the phylogeny of their hosts, thagus cannot remain in the genus Pelecanus along with onocrotalus if the genera Neopelecanus, Metapelecanus and Catoptropelecanus are to remain valid.

During the early years of this century, several new species of ticks were described from Western Australia, but since then the group has been neglected, with the result that no species have been added since 1909. In the course of some recent studies of the local ticks, an undescribed species of the genus Ixodes was obtained, of which a description is now given.

Habitat and Record. By the courtesy, and at the request, of Louis Page I have examined a specimen of Pennella ♀ from the Muséum National d'Histoire Naturelle, Paris, taken at Concarneau, Brittany, on 22. vii. 30, embedded in the skin of an albacore, Germo alatunga (Gmelin).

1. Two species of endoparasites, a Chalcid Stenomalus micans and a Braconid Coelineus niger, were found in every sample of “gouted” barley examined from a number of counties in southern England.

2. Chlorops infestations were severe in 1928 in many districts, and the majority of the “gouted” shoots were of winter-type damage, of which 68 percent. were parasitised, two-thirds by S. micans.

3. The larval anatomy of S. micans is described:

(a) There are five larval instars, each of which is described.

(b) The first larval instar appears to be partly predaceous.

(c) The larvae can be kept alive for 5 days on the surface of normal physiological saline solution and moulting occurs, which enables the instar to be determined with certainty.

(d) The tracheal system is devoid of spiracles until the fourth larval instar; spiracles then develop and are connected to the former rudimentary stigmatic trunks prior to the death of the host.

(e) The fourth instar larva develops a cephalic boring armature which is used for breaking up the internal organs of the host and also to bore an exit hole through the latter's body wall.

4. The pupa of S. micans is described and sex differences are indicated.

Experiments were carried out to show the different hygroscopic properties of certain foods supplied to flea larvae. These show that larvae of Ceratophyllus wickhami require about 15 to 28 per cent, of water in their food. Dried blood, albumen (blood) and material from the bottom of a squirrel's nest were used.

Newly hatched flea larvae were fed on different substances at varying humidities and a constant temperature. A relative humidity of 80 per cent. gave the best results.

Dried blood is a convenient food for breeding flea larvae in the laboratory, and may be used with or without a mixing medium, such as sand. Albumen is a more simple food on which a few larvae will survive, but at lower humdities than dried blood.

Flea larvae will eat a great variety of other foods, including squirrel faeces, ground-up cockroach and dead adult fleas, but these do not provide a complete diet.

It does not seem necessary for the larvae to have dried blood from the host of their parents, rabbit or human blood being quite as satisfactory.

In September, 1930, Dr E. C. Faust brought back from the Coto Region of Northern Panama two young female spider monkeys (Ateles geoffroyi). On December 11th one of these died from an experimental infection of Strongyloides stercoralis, and at autopsy was found to be very heavily infested with lice. Previous to this date the monkey had been handled a number of times but no lice noticed, although the two monkeys had frequently been observed carefully examining each other for external parasites. It is believed that the subsequent separation of the two (November 22nd) combined with the victim's illness allowed the lice to multiply at a prodigious rate. The hairs practically all over the body were found to bear nits, frequently as many as three or four per hair. Only a few lice have ever been found on the other monkey in spite of several careful examinations.

It is now slightly more than 60 years since Piaget described as Haematomyzus elephantis an extraordinary insect found by him living as an ectoparasite upon an African elephant in the Zoological Garden of Rotterdam. The insect was considered by its describer to be a sucking louse, and this assignment has been accepted by almost all of the few entomologists who have since been privileged to examine specimens. Walker, who in ignorance of Piaget'os work, redescribed the species as Idolocoris elephantis, regarded it as constituting a new family of Hemiptera Heteroptera near the bed bugs. Since that time no one has questioned the belief that it is a sucking louse and for it Enderlein named a family, the Haematomyzidae, in the Anoplura.

During recent years numerous forms of ectoparasitic trematodes have been discovered on the gills and body surface of fishes in Australia. Their descrip tions have been published in papers by Johnston and Tiegs (1922), Miss Kent Hughes (1928), and Johnston (1930). For the relevant literature on similar forms from other regions these papers may be referred to.

In 1928, a collection of marine fish trematodes was made at the United States Bureau of Fisheries Station at Beaufort, North Carolina; thirty-six of fifty-one species of fishes examined contained trematodes; only one or two specimens of some species were examined. Only Monogenea were collected from Elasmo branchs. The following report includes the digenetic forms identified. Type specimens of all new species are deposited in the United States National Museum.

Only a few immature fragments found. Rostellar hooks 0·011–0·014. A spiny collar present posterior to rostellum. Attributed to this species by reason of its being the only cestode of the family recorded from this host, and by the agreement in size of the rostellar hooks. As the original description is so inadequate it is unfortunate that the present form is immature.