In 1909, and again in 1914, papers, recording cases of deformity in Ticks, were contributed to this journal, by Warburton and Nuttall, and Nuttall, respectively: since that time, numerous examples of malformation have been observed in the material examined by them and by myself, in the course of our collaboration in work on Ticks in general. Of these examples, the five which are described and figured below, are sufficiently striking to be placed on record. The figures have been drawn with the aid of the Abbe-Zeiss camera lucida, and, in each case, the degree of magnification is indicated by a scale representing a length of one millimetre.

Whilst engaged on protozoological investigations of dysentery and allied diseases in Mesopotamia I had the opportunity of examining the stools of a large number of hospital patients, both British and Indian, and of noting the presence of worm ova as well as protozoan parasites.

The coloration of Amblyomma hebraeum, A. gemma, Dermacentor venustus, D. variabilis and D. reticulatus niveus, as seen in living examples, is depicted for the first time, and the desirability of recording the colours of ornate ticks when alive is indicated.

A remarkable change in colour in living specimens of A. hebraeum is described and figured, this change taking place after a prolonged sojourn (74–141 days) upon the host. Such a colour change has not hitherto been observed in ticks. The difference in colour is seen in dead dried specimens but is not appreciable in those preserved in alcohol.

Since the immature stages of ornate ticks are inornate, and the colours change in adults of some species during prolonged periods of parasitism, it is evident that the coloration in adults must depend upon the accumulated products of metabolism beneath the chitinous exoskeleton, the regional distribution of colour depending upon special metabolic functions taking place in corresponding parts of the tick. The ornamental colour-producing layer can be scraped away from the underside of the scutum in most ornate ticks and it is removable from such ticks by the use of caustic potash.

The whitish or creamy coloration that is so characteristic of most species of Dermacentor and the three ornate species of Rhipicephalus that are known to science, appears on the other hand to depend largely upon inclusions or structural changes within the chitin itself, whence the persistence of the creaminess seen by reflected light in the caustic-treated ticks. Similar, but less distinct, appearances may be seen in ticks belonging to other genera. Dermacentor rhinocerotis, which does not exhibit creamy coloration but only dull yellowish spots when dry, is totally decolorized by caustic potash, whilst contrary to most species of its genus it shows metallic coloration in well-preserved specimens in alcohol.

The examination of caustic-treated specimens was carried out upon 31 species of ornate ticks, i.e. Dermacentor (8), Rhipicephalus (3), Amblyomma (15), Aponomma (4) and Hyalomma (1 species).

The coloration and creamy ornamentation, herein distinguished, appear to be confined to the thinner portions of the exoskeleton. That the characteristic dark markings correspond to thicker and more darkly chitinised portions of the scutum is demonstrable by dissections, caustic-treated, or sectioned specimens; this being especially evident for instance in Amblyomma. The orange spot on the scutum of A. splendidum offers an exception.

The optical and chemical study of coloration in ticks deserves further investigation.

At the beginning of 1917 Professor V. Dogiel kindly handed over to me, for scientific treatment, a series of blood-films taken from different Amphibia, Reptilia, and Mammalia by the Expedition of Professors V. Dogiel and I. Sokolov to British East Africa in 1914. The films were examined by me for blood parasites, with the result that, of 27 animals, two different species of Bufo and two snakes proved to be infected. The blood parasites were represented by haemogregarines exclusively. The blood-films had been fixed on cover-slips by the dry method, and preserved in that condition for nearly three years. Altogether, I had at my disposal only 24 slips with blood-films taken from the peripheral blood of the infected animals.

During the summer of 1914 and during the months January to April, 1920, I have been able to investigate the Myxosporidian parasites of fish occurring at Plymouth, and I am glad to take this opportunity of thanking the Ray Lankester Trustees for their grant in aid of this research, and also to express my gratitude for the very valuable and kind assistance afforded me by the Director, Dr E. J. Allen, and staff of the Marine Biological Station at Plymouth, where the researches were carried out. The assistant Mr Smith helped me very considerably in the identification of the fish examined.

Amputation experiments upon immature stages of Argas persicus (Oken 1818), Amblyomma hebraeum Koch 1844, and Hyalomma aegyptium (Linnaeus 1746) show that the mouthparts and legs of these ticks may be more or less regenerated when mutilated shortly after the ticks have abandoned the host in a fully engorged condition.

Having during the last few years been particularly interested in the Nematode parasites of horses and donkeys I was very pleased to find a tube containing Strongyles from the zebra among some material recently forwarded to me by Professor G. H. F. Nuttall, F.R.S. These worms formed part of a collection of Helminths from Nairobi, British East Africa, which had been sent for identification by Mr R. Eustace Montgomery, Director of the Nairobi Veterinary Pathological Laboratory.

The great discovery of Sir Ronald Ross has not led to the suppression of malaria in the Netherlands' East Indian Colonies, where the disease is still all too prevalent. The failure is partly, if not wholly, due to the mistake that has been made in considering the facts revealed by this discovery as an all sufficient basis for practical sanitary measures, whereas they can only serve as a foundation for further research in which special and local conditions are taken into account, with the object of acquiring information which is essential for the success of a sanitary campaign.

During the last few years our knowledge of the Sclerostome parasites of the horse has been greatly augmented, the nematodes of the donkey have not however received attention since 1901, the date of publication of Looss' famous monograph on the Sclerostomes of the Equidae.

The Dipterous Family, Tachinidae, comprises a very large number of species whose larvae live as parasites within other insects, particularly in their larval forms.

This short account of the capitulum and mouth-parts of Psoroptes has been prepared as a preliminary to investigations which are being made upon the bionomics of the Itch Mites. None of the published figures or descriptions are complete. The best is that of Mégnin.

1. A parasitic spiral organism averaging 4 to 8μ long, with regular, closely set spirals about 0·75μ broad, has been found in the stomach in eight cats, none of which showed any obvious signs of gastric disturbance. The organisms occurred in the lumina of ducts and glands throughout the stomach, and also within the oxyntic cells. They were not seen in any part of the intestines except the very beginning of the duodenum, or in any other organ.

2. They are extremely active, and are readily stained by aniline dyes.

3. The mode of passage from one animal to another is not known, but food and faeces may be eliminated as possible sources of infection.

In 1851, Bilharz (1852) first discovered paired adult trematode worms originally named after him in the portal system of an Egyptian fellah. Subsequently, investigations of the deposits of ova in excreta were made, but numerous attempts by Cobbold, Sonsino, Lortet and Vialleton (1894) and others, to unravel the life history of the parasite, failed. Looss (1896), appreciating that the digenetic trematodes must necessarily pass through a molluscan intermediary, dissected many species of snails collected from the fresh-water canals around Cairo. He failed to find the cercariae of bilharzia, and discarded the hypothesis of an intermediate molluscan host. As, however, the miracidium of Schistosomum haematobium contained germinal cells within its body cavity, it must, naturally, he argued, have been destined to produce sporocysts at some stage of its life cycle. In view of this, Looss evolved the hypothesis that man acted simultaneously as the intermediary, as well as the definitive host of this parasite.

For several years Dr F. G. Cawston of Durban, Natal, has been making examinations of various mollusks taken from the rivers and pools of the Transvaal and Natal in order to discover the fluke infection of the region. These examinations have been extensive as regards the number of individuals of each species examined, ranging up into the thousands for the more common gasteropods. The investigations have been carried on through the various seasons of the year so that the data are representative. I have been enabled to re-examine much of this material through the courtesy of Dr Cawston, who has also placed at my disposal many of the biological data concerned with these researches.

Papio cynocephalus from French Guinea frequently harbours Loa papionis n.sp. The intermediate host is unknown. The larvae, in contradistinction to those of the human parasite Loa loa, show no diurnal periodicity.

The occurrence of bacterial disease in adult L. papionis would seem to be a novelty; at any rate I could find no mention of diseased filariae in the literature.

In so far as the biology of Microloa loa is concerned, I am inclined to doubt the correctness of the opinions expressed by Rodenwalt and Fülleborn concerning the structures they term “executory and genital cells”: the current hypotheses concerning the significance of these structures and of the “central viscus,” clearly need revision. Manson's “buccal apparatus” would seem to be nothing more than an optical illusion, while the “neck” or “shoulder” described by the older observers as existing in adult L. loa after fixation, was evidently due to imperfect technique.

I have drawn attention to the desirability of standardising the technicalities which are such essential preliminaries to the accurate mensuration of micro-filariae, and have suggested a method which has certain advantages over those at present in use.

Concerning the pathology of Loa infection, evidence both of the traumatic and toxic action of L. papionis on baboons, was obtained; moreover these parasites seemed definitely toxic for guineapigs, although the single experiment performed needs confirmation. The available evidence favours the supposition that adult baboons from an infected area possess a high degree of immunity both against L. papionis toxaemia and against reinfection by these parasites; but whether their serum is of therapeutic value for human beings infected with L. loa, requires further investigation.

In August, 1920, Dr Andrew Balfour, C.B., C.M.G., Director of the Wellcome Bureau of Scientific Research, received from Mr A. Pomeroy, F.E.S., Official Entomologist in South Nigeria, a tube containing some parasites from the “fore-gut” of a Cobra (Naia nigricollis Reinh.) from Ilaro, South Nigeria. Dr Balfour kindly handed these specimens to me for examination. The specimens were few in number, comprising only ten Nematodes and the two examples of Porocephalus described in the present Note. One of these examples at once attracted my attention by reason of its remarkable external form (Text-figure 1, A). I have consulted most of the available literature dealing with Porocephalus and the figure which, so far as I have discovered, most nearly approaches that of the present specimen is that of P. annulatus Baird, supplied by Shipley (his Text-figure 5, p. 59) in his memoir on the Linguatulidae. From my reproduction of Shipley's figure (Text-figure 1, C) it will be seen that Porocephalus annulatus, like the new species nowto be described, has a very narrow “neck,” but whereas in P. annulatus this neck is very short, in the new species it is comparatively very long; moreover, whereas in P. annulatus the cephalo-thorax (prosoma) is not longer than broad (or only slightly so in some specimens) and the first annulus of the “abdomen” (opisthosoma) is certainly no larger than succeeding annuli, in the new species the prosoma is roughly three times longer than it is broad and the first annulus is at least twice the size of the third at any succeeding annulus.

During the course of investigations, primarily directed to a study of the effects of hookworm infection on people in different parts of the tropics, I have been struck with the peculiar geographical and racial distribution of the two common species of hookworms infecting man, and with its bearing on certain ethnological problems.

The following observations are the result of two years' examination of the stools of patients invalided to and stationed in Malta. The patients may be roughly divided for convenience into four groups:

(1) Troops sent straight from the Salonika Hospitals to Malta. This section comprised the bulk of the total number of troops examined, and included a few men from Egypt.

(2) Garrison Troops—some not patients—including both British and Maltese. With these are included a few British and Maltese Civilians,. connected in some way or another with the Army.

(3) Troops on their way out from England or France. These were mostly Indians and Chinese, who were put off transport at Malta owing to disability.

(4) Prisoners of War interned in Malta.

The object of this paper is to draw attention to certain grave sources of error underlying the present mode of differentiating Anoplura and more especially species of the sub-order Siphunculata. I am unable to say if the criticisms herewith advanced apply equally to the methods employed in differentiating members of the sub-order Mallophaga, because I am not familiar with the latter group, but the two sub-orders mentioned are in many respects so closely allied that it appears difficult to avoid the suspicion that the considerations herein contained may apply equally in both cases.

This memoir presents the results of the study of a number of specimens of Filariid worms from Cattle and other Ruminants which had accumulated during the last few years from various collections of Nematodes, sent to me for identification and laid aside for further investigation.