The hypothesis that human malaria is transmitted by mosquitoes was canvassed by Laveran, Manson, Bignami, Dionisi, Koch, and others in 1895–1897—to mention no earlier speculators. But when, and by whom, was this hypothesis converted into a fact?

1. Ixodes holocyclus is a three-host tick.

2. It is found on native mammals, being abundant on Perameles nasuta (the bandicoot), while it has also been found on dogs, cats and man, and exceptionally on the large bush opossum and the rat.

3. Eggs hatch in from 49–61 days in warm weather.

4. Larvae harden and become active in about seven days, and engorge on host in 4–6 days.

5. Larval metamorphosis is prolonged by cold, and is most rapid in warm weather, varying from 19–41 days.

6. Nymphs harden and are quiescent for about seven days, and engorge in 4–7 days.

7. Adults emerge from larval skin in 21–71 days.

8. Coupling occurs away from the host and may last 11 days.

9. Adults harden and seek the host in about seven days and engorge in from 6–21 days.

10. Males are only rarely found on hosts, and have never been found attached or showing signs of engorgement.

11. Oviposition begins 11–20 days after the female leaves the host, and may last from 16–34 days; the number of eggs laid being about 1800–2500.

12. All stages are soon killed by desiccation, gorged nymphs and larvae being very soon killed even at moderate temperature.

13. A mass infestation with Ixodes holocyclus has not been seen either on native or domesticated animals.

The reputed toxic and destructive action of certain species of Chara led to the preparation of watery and alcoholic extracts of Chara foetida and C. hispida which were sent to me with the request that the larvicidal power of these extracts should be tested.

In laboratories which are situated either abroad or in districts at some distance from commercial centres, it often happens that needed apparatus is difficult to obtain, and these notes may be helpful to workers in such situations.

In the body-cavity of a Racket-tailed Drongo (Dissemurus paradiseus) which died at the Calcutta Zoological Gardens, and the blood of which was teeming with two species of microfilariae, were found males of two new species of filariae, together with a single female specimen. In a Hunting Cissa (Cissa chinensis), which died at about the same time, males of one of the species discovered in the Drongo were found again, accompanied by a single female different from that found before. Since this cissa also harboured two species of microfilariae in its blood, the identity of either of the females is doubtful. In another specimen of hunting cissa a single male specimen of an entirely different species, which I have made the type of a new genus, was found. Here again two species of microfilariae were discovered so that it is not possible to say which is the offspring of the adult found. It had been hoped that more infected specimens of these birds might be obtained so that the confusion as regards relationships of the females and offspring to the males might be cleared up, but there appears to be little hope of more being obtained in the near future.

The following paper is part of the result of work done in the University Museum of Zoology, Cambridge, between Nov. 1922 and June 1923. The present writer has for some years been receiving specimens of Nycteribiidae for determination, and with them there had accumulated at Cambridge a small collection of another family of bat-parasites, the Streblidae. At the writer's suggestion, Mrs Kessel undertook a systematic examination of this collection, and with it of material kindly lent by the British Museum through Major Austen and Mr F. W. Edwards, by Professor Poulton from the Hope Museum, Oxford, by Dr G. A. K. Marshall from the Imperial Bureau of Entomology, and by Mr S. Hirst. To all these gentlemen thanks are tendered, also to the authorities of the British Museum for the gift of certain named duplicates, and to Mr Oldfield Thomas for checking the names of the mammalian hosts. Thanks are also due to Mr Gillings for the care exercised by him over the drawings, and to the editors of Parasitology for accepting this paper for publication.

Dr Woodland kindly submitted to me the majority of the worms recovered by him on dissecting the mice used in his very interesting experiment (see his paper that follows), with a request for my opinion as to the identity of the species. The material, which was handed to me preserved in formalin, consisted only in part of complete specimens, a number of the worms having been broken up during collection. I stained most of the whole specimens with dilute haematoxylin and mounted them in Canada balsam. Upon microscopic examination it became evident that the specimens were of various ages and degrees of maturity, and one specimen was of exceptionally large size. This individual, in a fairly contracted condition, measures (after mounting and without stretching) 36 mm. in length, and has about 650 recognisable segments. Mature segments (i.e. segments with testes and ovary both fully developed) begin to appear-at about the 320th segment from the scolex, and gravid segments at about the 490th. There are thus about 160 gravid segments. It will be evident from these details that this specimen agrees with my description of “Hymenolepis longior.” Two of the young forms among Dr Woodland's material also seemed to agree with “H. longior” rather than with what I had regarded as H. nana.

Although the common Filariid parasite of the Camel was identified as a distinct species more than forty years ago (Lewis, 1882), the recent memoir on Indian Nematodes by Baylis and Daubney (1923) contains the first intelligible account of the structure of the adult worm. Their description of the species, which they refer to the genus Acanthocheilonema, is based partly on some rather fragmentary material received from the Zoological Survey of India, and partly on notes and drawings supplied by Major F. H. Stewart, I.M.S.

1. Out of 57 mice (previously ascertained to have been free from “H. fraterna”) 30 were fed on fresh eggs of Hymenolepis nana, the other 27 serving as controls. Out of the 30 egg-fed mice, only 7 were found to be infected (23·3 per cent.) when examined from thirteen to twenty-six days afterwards. None of the 27 control mice showed infection.

2. This low percentage of infection (when compared with the 90 per cent, infection obtained in my previous work when I fed 20 mice on “H. fraterna” eggs) is probably due to one or more of three factors: (a) change of host (Grassi records that he found it very difficult to infect wild rats with “H. fraterna” eggs obtained from tame rats and in this case the animals were of the same or closely allied species); (b) the full-grown adult condition of the mice; (c) the perfect health of the mice, due to having been supplied with vegetable food (Vitamin B) every day, this condition rendering the mice refractory to infection. In my previous work the mice were in poor condition owing to deficiency of Vitamin B.

3. The proof that rats and mice can be infected with H. nana eggs from Man, the identity of structure of the two parasites and their eggs and their uniform geographical distribution render it practically certain that H. nana and “H. fraterna” are one and the same species. The fact that up to the present there is practically no evidence that Man can be infected with eggs derived from rats or mice does not militate against this conclusion.

4. Mature specimens of H. nana found in tame mice vary enormously in size (as already indicated by Joyeux)—between 7 mm and 80 mm. (measured in balsam) in length. “H. longior” (Baylis, 1922) does not exist as a distinct species.

5. I failed to infect two Cercopithecus monkeys fed with a plentiful supply of fresh H. nana eggs (from Man).

6. Experiments are described which confirm Joyeux's statement that H. diminuta (of the mouse), unlike H. nana, does not possess a direct one-host life-cycle.

The monogenetic trematodes have long been known as parasites of the lower aquatic vertebrates and many forms have been described from fishes, amphibians, and reptiles. They are largely ectoparasitic, although a few members of the group infest the oronasal cavities and urinary bladder of frogs and turtles. Up to the present there appears to be no record of their occurrence on either birds or mammals and consequently the unusual case here reported seems worthy of note. The material consists of five polystomes which bore the label, “from the eye of hippopotamus.” Presumably they were collected by the late Professor A. Looss from a Nile hippopotamus in the Giza Zoological Gardens of Cairo, Egypt, but unfortunately no particulars are available. The specimens were given to me for identification by Dr Edward Hindle, recently Professor of Biology, School of Medicine, Cairo, to whom I wish here to express my thanks. Grateful acknowledgments are due also to Professor George H. F. Nuttall, Director of the Molteno Institute for Research in Parasitology, where the study was made.

1. A new species of Bothriocephalus—B. pycnomerus—is described from the intestine of Ophiocephalus marulius Ham. Buch., from the Ganges and Jumna at Allahabad, India.

2. B. pycnomerus closely resembles B. histiophorus (Shipley 1901; from the marine sword-fish Histiophorus) in structure but differs chiefly in the possession of an armed scolex and its crowded indistinct segmentation.

3. Lühe's definition of the genus Bothriocephalus must be amended to include forms with armed scolices and forms in which the ventral uterine apertures are a-median and irregularly alternate.

4. Two new species of Proteocephalidae are described which possess armed muscular rostella, and for these a new genus Gangesia is created and defined. The definitions of the Order Tetraphyllidea (Lühe 1910) and of the Family Proteocephalidae (La Rue 1914) must be amended to include forms possessing muscular rostella, armed or unarmed.

5. These two new species—Gangesia wallago and G. macrones—were found in the intestines of Wallago attu Bleek and Macrones seenghala Sykes (both Siluroids) respectively, from the Ganges and Jumna at Allahabad.

6. Southwell's “Ophryocotyle bengalensis,” from Ophiocephalus striatus, Labeo rohita and Wallago attu, is probably identical with Gangesia wallago.