Set of seven of these nematodes, two males and five females, taken from a fresh-water tortoise from Tasquillo, State of Hidalgo, Mexico, collected in 1937.

Previous workers have described the curious method by which the female bed-bug is fertilized. They have suggested that the large quantity of sperm injected serves some function other than that of fertilizing the egg.

The rate of metabolism of the virgin bug is much less than that of the fertilized female.

Ovarian development never occurs until the female has been fertilized. After fertilization, egg development is apparently controlled by a hormone produced by the corpus allatum.

Living sperm will always be found in the spermathecae of females which are laying fertile eggs.

The so-called imperfect eggs produced when the sperm is exhausted are normal save for being unfertilized. They have been considered as malformed because of their tendency to shrivel quickly in dry air.

Sperm remains viable in the female for a definite period depending on the temperature. This period is longer at low than at high temperature. Provided a certain minimum amount of sperm is introduced (this minimum is less than the quantity introduced by a well-nourished male at one copulation), the period of viability of sperm is the same no matter how many eggs are produced. The number of eggs depends only on the amount of food taken.

There is no evidence that the sperm serves any nutritive function in the female.

Some years ago the South African Museum received a tube of mites taken from the South African scaly anteater, Smutsia temmincki, by Dr R. Bigalke, Director of the National Zoological Gardens at Pretoria. The tube contained more than 200 well-preserved gamasid mites, and I wish to express my thanks to Dr Bigalke and the authorities of the South African Museum for affording me this opportunity of studying these parasites.

A natural infestation of bed-bugs which has existed for several years in an animal room has been studied. The bugs feed on the rats kept in cages in the room.

Methods are described by which the bugs were trapped during their periods of normal activity.

Adult bugs appear to feed on an average once every 5 or 6 days when the temperature is in the region of 20–27° C. (68–80·6° F.). Most of the female bugs lay a continuous series of eggs at the rate of nearly three per day.

Female bugs are not usually fertilized more than once a week in this wild population. In laboratory cultures copulation is much more frequent.

In the animal house the bugs were most active between 3 a.m. and 6 a.m. This activity seems to be controlled by some inherent rhythm.

Some marked bugs were released and the proportion of recaptures to others in the total catch was noted. From this a rough estimate of the population was made. It appears that few adults live more than 29 days as they are probably killed by the rats when trying to feed.

1. Vogel's (1920) assertion that the labral canal is closed ventrally by apposition of the edges of the labral groove is fully confirmed. The hypopharynx plays no part in the ventral closure of the food canal except at its base. The somewhat popular term “labrum-epipharynx” is dispensed with in favour of “labrum”.

2. The mandibular teeth vary in number round about 40. The mandibular suspension is fully described.

3. Evidence from musculature is put forward for the existence of a small maxillary palpifer not present in other Diptera.

4. Snodgrass (1935) criticizes Crampton's (1925) homologizing of the labella with labial palps because “the lobes of the fly labium have usually each only one muscle inserted directly upon it”, whereas palpi usually have antagonistic muscles. Vogel for Culex and this paper for Anopheles maculipennis show that the labial lobes of these insects have antagonistic muscles like typical palpi.

Cercaria strigata was first named and described briefly by Lebour (1908) from Tellina tenuis and Donax vittatus at Alnmouth, Northumberland. It was recorded again by the same author (1911) in 3% of Tellina tenuis at Millport. What was almost certainly the same cercaria had been previously noted by Giard (1907) between the mantle and shell in the same hosts. Giard did not name or describe the cercaria but suggested that it was the young stage of Gymnophallus oedemiae (Jameson) (= G. somateriae (Levins)) from the scoter Oedemia nigra L.

Examination of mite material sent from various sources for identification has revealed a number of new species. In this paper seven new species of Laelaptinae, one of Entonyssus and one of Listrophoroides are described.

Habitat and record. A single female was taken on Leiochone sp. by Alan Fisk on 23. viii. 1938 at Roscoff, France.

In 1935 I described a free-living flagellate, which bore a striking resemblance to the genus Trichomonas, and was obtained, on four different occasions during a period of 12 months, from a pond in Lincolnshire. This flagellate has three anterior flagella, and a short marginal flagellum bordering an undulating membrane but without a freely-projecting end. There is no basal fibre at the base of the short membrane. The three free flagella and the marginal flagellum arise from a blepharoplast which lies in front of the single, anteriorly placed nucleus. There is a cystostome. An axostyle frequently is absent, but when present it is slender and siderophilic. Division is similar to that of Trichomonas hominis and T. batrachorum (Bishop, 1931).

In a recent paper Dr L. R. Cleveland (1938) has published some observations on a remarkable flagellate called “Teranympha”, which was discovered nearly 25 years ago by Dr M. Koidzumi in the white ants of Japan. I do not now propose to discuss this singular organism itself, however, but only its name and certain other matters of wider interest which its nomenclature suggests—matters which seem to me, indeed, to merit the immediate attention not only of all parasitologists but even of zoologists generally.

During the investigations that have been carried out at this Laboratory into the factors concerning the development of the strongyloid diseases of grazing animals the requirement has been felt for some method whereby the infective larvae of the parasitic worms could be recovered from the pasture herbage and an estimate made of the relative extent of infection, or possibly, of the actual number of larvae available to the grazing animal.

1. The mosquito fauna of the Cambridge district, which includes a large stretch of cultivated fenland, is compared with that of the “natural” fen at Wicken and also with that of other districts.

2. The ecology of the various species is discussed and the conclusion is reached that the main factor determining why different species are found in different types of habitat is the time of year at which the female lays her eggs, and whether she lays them on damp ground or standing water.

The larvae and puparia of Limnophora exurda are to be found in tufts of wet moss or liverworts in or near small waterfalls.

The larvae are carnivorous and exhibit the characteristic morphological characters of carnivorous anthomyid larvae.

In the present paper I discuss the identity and systematic position of Synthesiostrebla amorphochili Townsend, Speiseria ambigua Kessel and Lemosia setosa Pessôa ão. Besides, I include in this paper a revision of the species of the genus Paratrichobius, which structurally is more or less closely related to the genus Synthesiostrebla.