The material here described was mostly obtained as a result of a period of study and travel in East Africa in 1939. Two of the species were reared from Coccidae of the genus Aspidoproctus at Amani, Tanganyika Territory, and their life, history is the subject of an accompanying paper. I am greatly indebted to Dr F. W. Edwards, F.R.S., for allowing me to describe the remarkable species collected by him on Ruwenzori, Uganda, in 1935. I am also most grateful to Dr R. H. Le Pelley of the Scott Agricultural Laboratories, Nairobi, and Dr E. A. Lewis of the Veterinary Research Laboratory, Kabete, Nairobi, for other valuable new material. In addition, The Imperial Institute of Entomology has kindly allowed me to examine and describe material from Uganda in their possession which had been erroneously identified as Cryptochaetum iceryae (Will.). Type specimens of all species will be deposited in the British Museum.

An Ischnopsyllus Westw., 1833, lately sent by Miss Kuei-Chen Li, National Kweiyang Medical College, China, differs considerably from all the known Ischnopsyllus and suggests that the species are as numerous in China as in Europe. Inclusive of Miss Li's specimens four eight-combed species from China are represented in the British Museum, all that have so far been described from that country. We are much indebted to Miss Li for the new species and to Mr Yin-ch'i Hsü for paratypes of two bat-fleas described by him

1. The development of Theileria parva in engorged larvae of R. appendiculatus exposed to a temperature of 4–6° C. for 3 days at intervals of 2, 4, 6, 8 and 9 days after repletion is not retarded; and it appears, from previous experiments and those now described, that, as long as the tick survives, climatic conditions do not kill or weaken the parasite.

2. The virulence of East Coast fever transmitted by ticks fed in the tail brush did not differ from the disease conveyed by ticks infesting the ears.

3. Reference is made to records of mild reactions to Bast Coast fever when the parasites are either rare or absent; and instances are given of such reactions followed by recovery in experimental animals. Although the mild form of the disease seems associated at times with light tick infestation, it is proved that a few infected ticks also transmit a fatal East Coast fever. It is shown also that ticks fed on a bovine during a short or mild reaction can produce a virulent form of the disease in susceptible animals, and that mild reactors acquire an immunity to the virulent disease.

4. The experiments which are described indicate that ticks do not become infected with T. parva from the blood of a bovine for the first 4 days of the reaction period.

5. Evidence is produced which strongly suggests that T. parva tends to disappear from infected hungry ticks kept under laboratory conditions for about a year or more. The age of the tick would appear to be an important factor in the transmission of East Coast fever.

6. Attempts to break down the immunity to East Coast fever, and to produce “turning-sickness”, by massive infestations of ticks were unsuccessful; and further experiments on the transmission of East Coast fever by ticks which had fed on animals suffering from “turning-sickness” did not confirm earlier positive results.

These conflicting results may be explained by the observations that “turning-sickness”, associated with the blocking of the small capillaries of the brain by lymphocytes containing schizonts indistinguishable from the Koch's bodies of T. parva, may be divided into three stages, namely, acute, subacute and chronic; and it is suggested that infection of ticks with T. parva from “turning-sickness” could normally be successful only from animals in the acute and early part of the subacute stages since piroplasms disappear from the peripheral blood stream in the more advanced cases of “turning-sickness”.

7. The opinions of other workers on East Coast fever are discussed in the light of the experiments carried out at Kabete and of field experience in Kenya Colony. It is explained how the results can be applied to the movement of cattle from endemic areas over country free from East Coast fever.

On 6 November 1939, shortly after the invasion of Poland, the professors at the Jagellonian University of Cracow were summoned to attend a lecture on “Nazi Science”, to be delivered by a high German official. Those who obeyed the order were arrested. The charge brought against them was, in brief, that they had been attempting to fulfil their duties at the University, and were thereby guilty of striving to keep alight the flame of Polish national culture. For these offences the unfortunate professors—some of them old and feeble— were imprisoned and robbed of their property. After being jailed in Cracow they were taken to a convict prison at Breslau and thence to a concentration camp at Sachsenhausen-Oranienburg (near Berlin)—where, of course, many of them died.

Tropical and certain parts of subtropical Africa constitute the home of the genus Aspidoproctus (Coccidae, Monophlebini). The genus is remarkable in several ways, but chiefly because of the very large size attained by some of the species. A. maximus and A. giganteus are almost certainly the largest scale insects in the world, the female being well over 1 in. long and as much as ¾ in. thick. Owing to the relatively degenerate structure of scale insects in general, and in particular because of the poor development of the circulatory and tracheal systems, the biology of scale-inhabiting parasites is always of interest. This is particularly the case in relation to problems of respiration, and many scale parasites are already known (Thorpe, 1931, 1934, 1936) which exhibit very striking respiratory adaptations. Previous to the present paper no parasites had been recorded from the genus Aspidoproctus, yet it appeared extremely improbable on general grounds that these insects were immune from the attacks of the usual dipterous and hymenopterous parasitoids. Accordingly, when opportunity came to visit East Africa, attention was directed particularly to this problem; for it was felt that with insects of such large size and having such a thick dorsal cuticle, the problems to be overcome by the internal parasite would be intensified tenfold, and that any species found would be likely to exhibit structural and physiological adaptations of unusual interest. That this is indeed the case the present paper will show.

1. The structure of the proboscides of the larva of Dibothriorhynchus grossum (Rud.) is described. Each proboscis is provided with four sets of extrinsic muscles, and there is an anterior dorso-ventral muscle mass connected to all four proboscides.

2. The musculature of the body and scolex is described.

3. The nervous system consists of a brain, two lateral nerve cords, two outer and inner anterior nerves on each side, twenty-five pairs of bothridial nerves to each bothridium, four longitudinal bothridial nerves connecting these latter before their entry into the bothridia, four proboscis nerves arising from the brain, and a series of lateral nerves supplying the lateral regions of the body.

4. The so-called ganglia contain no nerve cells, these are present only in the posterior median commissure which is therefore the nerve centre.

The materials for this paper were obtained from three sources: (a) the examination, on successive occasions during the period December 1939–April 1940, of volunteer subjects, mainly from common lodging houses in east London, prior to their treatment with pediculicides, (b) the examination, during April 1940, of large numbers of men from common lodging houses, Salvation Army hostels, night refuges and other sources, in a search for further suitable subjects for control experiments, and (c) the study of the process of infestation of shirts issued to selected volunteers and worn continuously over a period of 10 days. The material from the first source is largely selective, since infested volunteers were specifically invited; that from the second source is more representative of the population of cheap hostels, since no emphasis was laid on the presence of lice, the men being induced to submit to examination by the offer of payment. It is, however, obviously not a random sample since it represents volunteers, and neither it nor the source (a) material should be used as a measure of the frequency or degree of infestation normal to the corresponding group of the city population.

1. While investigating the parasites of the holly leaf-miner (Phytomyza ilicis Curt.) with a view to utilizing them in the control of this troublesome pest of holly in western Canada, a species of Opius, which on examination proved to be new to science, was reared from the fly puparia.

2. A fairly complete account of the general systematics, distribution, biology, and morphology of the various developmental stages of this parasite is set down in the preceding pages. The primary larva is particularly interesting because of its unusual orientation. After the anatomical details had been worked out it was discovered that the concave side of the larva, which would normally be regarded as the ventral surface, is actually the dorsal one.

3. The genus Opius, whose distribution is world-wide, contains a very large number of species which parasitize important economic pests. In temperate regions the insects which suffer most from their attacks are species of Pegomyia, Agromyza, Rhagoletis, Phytomyza and Cerodonta, whilst in tropical and subtropical areas the most favoured hosts belong to one or other of the two genera Dacus and Anastrepha.

4. The host relationship of the genus, because of its importance from both economic and taxonomic standpoints, is discussed at some length.

5. In the first stadium Opius ilicis is a larval parasite, but the three succeeding instars live in the host pupa, and the imago emerges from the puparium. A very interesting phase in the life history of this parasite occurs towards the end of the first stage. At this point the development of the larva is arrested and further growth cannot take place until the host has pupated.

6. Very little work has so far been carried out on the larval morphology of the Opiinae, but that done up to the present, including the foregoing descriptions, would seem to indicate that the larvae of this tribe form a fairly homogeneous group. The main distinguishing characters of these larvae are listed in section VII of this paper.

7. It is pointed out that O. ilicis, in spite of being intrinsically inferior to Chrysocharis gemma, is responsible for the destruction of a certain number of hosts which escape the attentions of the latter parasite, and although the percentage accounted for is small (maximum parasitism in 1939 4%), it nevertheless fills a particular niche of its own, and so must be of some definite value in the scheme of control.

8. The chief method employed by the first instar of Chrysocharis gemma in the destruction of rival Opius larvae would appear to be direct mandibular attack. Several reasons have been put forward to account for the decided inferiority which is exhibited by the Braconid when it comes into conflict with this Chalcid.

9. In section X, a number of interesting points which have a general bearing on the study of parasite larvae are discussed. These include the cephalic skeleton and its probable function in successive instars, the taxonomic value of this structure in the parasitic Hymenoptera, the apparent absence of a tracheal system in the second and third instar larvae of O. ilicis, and arrested development in the Opiinae and some related forms.

The aspidogastrid trematodes form a well-defined group of at most eight genera with a wide distribution. They are known from five continents and they occur in various cold-blooded hosts from both marine and fresh-water habitats, notably, Gasteropod and Lamellibranch molluscs, the larger Crustacea, some Fishes, and Chelonians. The recording of a new genus in a fresh locality is thus of some zoological importance.

We received from Dr W. H. Thorpe a remarkable Eupelmid bred from the large Coccid, Aspidoproctus maximus Newstead, in East Africa. As Dr Thorpe has been able to make some interesting observations on the life history of this parasite, I have been asked to study it specially. It differs from all other known species of Eupelmus from Africa, and I am giving here a description of that species.

1. Isolated unmated female body-lice were worn in pillboxes between the skin and the clothes. They were kept constantly on the body but, by a simple device, groups of ten were permitted feeding periods of different length. These groups were fed for 4, 8, 12, 16, 20 and 24 hr. per day respectively. Another group of ten were never allowed to feed after the last moult.

2. Some of the figures for egg yield were high. Lice in the 24 hr. group were able to maintain a rate of ten eggs per day for 4−5 days at a time.

3. No significant difference in longevity or rate of egg-laying was found to exist between the 12, 16, 20 and 24 hr. groups nor between the 4 and 8 hr. groups but a pronounced and significant difference exists between the 8 and 12 hr. groups. Below 12 hr. there is a sharp fall in longevity and rate of egg production. The unfed group all died, without laying, on the third day.

4. The rate of laying as shown by the mode increases progressively with increase in time allowed daily for feeding.

5. With regard to the mean eggs per louse the position is less clear. It is felt that the 24 hr. group may differ significantly from the 12, 16 and 20 hr. groups but this is uncertain.

The trematode and cestode parasites of fishes inhabiting British coastal waters have been the subject of several studies in the past, but the parasites of deep-sea fishes have received comparatively little attention due probably to the difficulty of obtaining fresh material. In order that such material might be obtained, excursions were made by the junior author in a commercial trawler to some of the deep-sea fishing grounds lying to the west of Ireland, namely, the Irish Atlantic Slope and the Porcupine Bank. Two excursions were made, the first in August 1938 and the second in July 1939, each extending over a period of about 12 days. In addition, a study has been made of the parasites of some fishes from the Irish Sea from 1936 to 1939. The results of both surveys are incorporated in this paper, and the areas investigated are indicated in Table 1.

1. The egg distributions of five chalcid parasites of the knapweed gall-fly have been studied in a small area.

2. A distinction is made between search for hosts by random movements, and random search in the sense of Nicholson; these terms are defined. Random movements may give rise to a distribution of parasitism different from that expected if search were purely random.

3. The species discussed do not all distribute their eggs at random amongst the hosts. Some species superparasitize the hosts more, and one (Eurytoma curta) much less than would be expected if the egg distribution were purely random, owing to peculiarities in oviposition behaviour.

4. Parasitism by E. curta is unevenly distributed in space, being higher in areas of high host density. This suggests that search is not exactly random, but is also concentrated in space. A tentative explanation is advanced based on the assumption that search is by random movements.

5. Parasitism by E. robusta is very patchy. This non-random distribution is attributed to random movements performed by a very few parasites.

6. It is concluded that these spatial discrepancies do not seriously affect the numerical accuracy of the assumption that search is random in small areas, and that the theory of Nicholson & Bailey may be accurate to a first approximation.

Prof. P. A. Buxton sent me a number of tubes of mite material to examine, and in one bearing the label ‘Gerbille, Madras, India, 3. v. 37, C. S. Swaminath’, I found a number of mites of the genus Laelaps, which were obviously new, in so far as the shape of the anal scutum was decidedly wider than any known species of this genus. This species I have herein described under the name Laelaps buxtoni

The present work, fills in some of the gaps in the morphological descriptions of Hemimerus, as given by Hansen (1894) and Jordan (1909), and deals with the details of the anatomical modifications associated with the semiparasitic mode of life.

It seems that this semiparasitic mode of life is of mutual assistance or “symbiosis”.

The modifications are seen in the mouthparts (especially the ligula and the superlingua), pleural sclerites and the thoracic limbs.

1. Choricotyle chrysophryi van Beneden & Hesse has been recorded for the first time since its original discovery in 1863, and from a new host Pagellus centrodontus (De la Roche).

2. The history of C. chrysophryi and of allied species has been reviewed, resulting in the substitution of the generic name Choricotyle van Beneden & Hesse, 1863 for Diclidophora Goto, 1894 and the family name Choricotylidae nov. for Diclidophoridae Fuhrmann, 1928.

3. The anatomy of Choricotyle chrysophryi has been investigated by means of serial sections, revealing specialized features in the presence of a terminal languette and of a ‘ring-organ’.

(i) Sensory responses

The reactions of the body louse to temperature, humidity, smell, contact and light have been tested in an arena divided into two halves.

Temperature. A temperature of 29–30° C. is preferred before 32° C. or 27° C. As the alternative temperature rises above 32° C. or falls below 27° C. the avoidance becomes increasingly strong. Different individuals vary in sensitivity.

These results are in accordance with those observed in a linear gradient of temperature, in which the lice collect chiefly in the region from 28 to 31° C.

The response is always to air temperature; there is no response to radiant heat from objects at 20–45° C.

Humidity. The louse is generally indifferent to humidity over the range from 10 to 60 or 75% r.h. Higher humidities are avoided. But when offered two humidities the choice is greatly influenced by the conditions experienced by the louse in the immediate past; it avoids any change; hence different individuals may show quite different responses. Moreover, when offered the choice of very moist air (95 % r.h. or over) and very dry (47 % r.h. or under) the louse becomes more readily adapted to the moist air and begins to avoid the dry.

Smell. The louse prefers cloth that has been in contact with human skin to clean cloth or cloth smelling of dog or rabbit. The smell of other lice and of their excreta is also attractive. Many substances serve as repellents; a refined petroleum with a very faint odour has been chiefly used for the experiments.

Contact. When offered smooth and rough materials the louse chooses the latter. It moves more rapidly on smooth materials and does not come to rest so readily. It shows little response to air currents unless very strong, when they are avoided.

Light. The movements of the louse are arrested or retarded by sudden exposure to a bright light, and sometimes it may show avoiding movements. But the movement of the louse towards dark places is mainly a response to directed light received by the horizontally placed eyes. Slight differences in the light received from different directions exert a much greater effect if the louse is exposed to a low level of general light intensity.

The movement of the louse towards relatively small dark objects is probably a manifestation of the same response.

An account is given of some Microsporidia found in certain fishes and insects in eastern Canada, among which are new species of Nosema, Perezia and Gurleya.

Nosema pimephales n.sp. produces large cysts or tumours in the abdomen of Pimephales promelas, one out of a large number from Lake Guindon, Province of Quebec, being infected.

Nosema branchiale Nemeczek has been observed from a cod, Gadus callarias. The organism is shown to be a Nosema, though the incomplete original description has caused doubts as to whether some other genus was involved. Further details are now given.

Nosema apis Zander and N. bombi Fantham & Porter have been found in Canada in hive-bees and humble-bees respectively, the latter being recorded from a new host, Bombus vagans.

Glugea hertwigi n.var. canadensis is described from Osmerus mordax from Lake Edward.

Perezia aeschnae n.sp. has been found in nymphs of the large dragonfly, Aeschna grandis, collected near Montreal and is described and illustrated.

Perezia legeri Paillot has been observed in larvae of Pieris brassicae.

These appear to be the first records of Perezia from insects in North America, and the zoogeographical distribution of the genus is extended to the Odonata.

Gurleya aeschnae n.sp, is described from a nymph of Aeschna grandis. It is the first species of Gurleya to be described from the Odonata and the first record of the genus from the North American continent.

Thelohania corethrae Schuberg & Rodriguez is described from the larvae of Chaoborus flavicans. Measurements of the parasite, which were lacking in the original description, are now supplied.

Thelohania bracteata from larvae of Simulium bracteatum and larvae and one adult S. venustum and Thelohania fibrata from larvae of Simulium venustum are recorded from places in the Province of Quebec. The need of reinvestigation of the species of Thelohania from various Simulium and the possibility of there being but one species, Thelohania varians Debaisieux, are indicated.

Thelohania legeri Hesse is recorded as a parasite of larvae of Anopheles punctipennis in Quebec Province and of A. gambiae in Zululand. It is probably the most widely distributed species of Thelohania, occurring in Anophelines in Europe, Asia, Africa and North America.

Some general remarks regarding zoogeographical distribution, habitat, host-specificity and possible origin of species and varieties in connexion with Gurleya, Perezia and Thelohania are presented.

Samples of Peringia ulvae were collected and measured on eight occasions, over a period of two years from an isolated pool in the saltings of the River Tamar. Growth conditions in this pool are at a maximum. Spawning occurs in the autumn and the greatest number of small specimens are found in the sieve (1 mm. mesh) in February. Maximum growth takes place during April-July. After ten months of age,.uninfected snails which have reached a length of 5¾ mm. grow only 1–1¼ mm., and gradually die off from 17 months of age onwards. Infected snails display gigantism and variation and attain dimensions of 9–10 mm. They are probably no older than uninfected specimens measuring 6¾ mm. long.

The infection rate is high and shows certain seasonal fluctuations, no doubt linked with the migrations of the wading birds which are the principal final hosts of the trematodes.

Observed have been made on the life cycle of Ixodes ricinus, whilst rearing stocks of this tick in the laboratoy. Some larvae were found to undergo a prolonged metamorphosis into nymphs and periods of 341, 354 and 361 days between the start of larval engorgement and nymphal emergence are recorded. The rather exceptional conditions under which the ticks were kept are described as well as the methods of maintaining and feeding the specimens.