In a previous paper (1935) an account was given of the prostigmatic mites parasitic on South African lizards, belonging to the two endemic families, the Zonuridae and Gerrhosauridae. The present paper deals with the fauna of the two remaining families of lizards, the Geckonidae and Agamidae, parasitised exclusively by prostigmatic mites. Trägardh (1905) and Hirst (1926) have made the most considerable contributions to the knowledge of the parasites of Geckonid and Agamid lizards; the latter placed the group on a sound systematic basis, the former, in addition to his descriptions of new forms, contributed valuable notes on the development and morphology of the species studied. With regard to mite parasites, however, up to the present, no systematic investigation has been attempted of all the species belonging to any one family of lizards from a given zoo-geographical region. In the present paper this has been attempted; the great majority of Geckonid and all the species of Agamid lizards from the South African subregion, either as living or spirit specimens, have been examined; from most of them mite parasites have been obtained. Both families of lizards are, genealogically speaking, derived from a long-established, Saurian stock; both are, in South Africa, extremely well demarcated, homogeneous families, with their main structural characteristics varying within narrow limits. In neither of them does loss or degeneration of the limbs occur. Each family is parasitised by a single genus of prostigmatic mites, the Geckonidae by Geckobia, the Agamidae by Pterygosoma; while Geckobia is found on the Geckonidae and on no other family, Pterygosoma is also a parasite of Gerrhosaurid lizards on which three species have been found. In a previous paper by the writer (1935, p. 3) Pimeliaphilus was cited as occurring on Geckonidae. Trägardh, who erected the genus (1905, p. 31), actually found his species P. podapolipophagus living under the elytra of a beetle, Pimelia, but the other two species of the genus, P. insignis Berl. and P. tenuipes Hirst, both occur on Geckonid lizards. Neither of these two species have been found in South Africa and it is extremely unlikely that they occur in this region.

1. A detailed historical account of the subfamily Haplorchinae is given. The systematic position of the various species in this group is critically reviewed. The subfamily Haplorchinae and the genus Haplorchis are accepted as valid while Monorchotreminae and Monorchotrema as synonyms.

2. Three species of Haplorchis are found in Kwangtung Province, namely, H. pumilio (Looss 1896), H. taichui (Nishigori 1924), and H. yokogawai (Katsuta 1932).

3. Throughout the work emphasis is laid on the acetabular spines or hooks which are considered to be the only recognisable constant structure practical enough for specific diagnosis.

4. It is believed that there are only four valid species of Haplorchis, namely, H. pumilio, H. yokogawai, H. taichui, and H. milvi. The validity of H. milvi, however, is in question. H. cahirinus and H. anguillarum do not fit into the diagnosis of the subfamily Haplorchinae, while H. microrchia and H. taihokui fall into synonymy with H. taichui and H. pumilio respectively.

5. A key for the identification of the known species is given.

In 1933 Mr C. Machattie, F.R.C.V.S., D.V.S.M., very kindly sent me a small portion of a specimen of Lymnaea tenera euphratica Musson, collected in Iraq, infected with a cercaria belonging to the heterogeneous Gymnocephalic group. Sections were cut and it was found that most of the cercariae had been fixed during various stages of encystment. An excellent opportunity was thus afforded for observing this process, particularly the initial stages.

This collection, among others, was made for and kindly presented to me by Miss Miriam Rothschild during her visit to the Zoological Station, Naples, in April 1934.

Within recent years a considerable amount of work has been done on the Myxosporidia, especially, as pointed out by Kudo (1919), in North America, Asia, and to a lesser degree in Japan (Fugita, 1912, 1913, 1925). Few investigations, however, have been carried out in Australia, and consequently very little is known concerning the distribution of the group in this country. There appear to be as yet only two contributions to the subject, papers by T. Harvey Johnston and M. J. Bancroft (1918, 1919). As far as can be ascertained, my paper is the first report concerning Myxosporidia from fishes of Southern Australian waters, and contains the first record of a species of Chloromyxum from Australia.

The small group of Trematodes here discussed comprises new species of the genera Megalocotyle, Calicotyle and Microcotyle.

Many biologists are at present interested in populations of animals, which are studied experimentally and also by more abstract mathematical methods, but it is frequently difficult to obtain facts about actual populations living under natural conditions unless they are studied by sampling, the accuracy of which cannot always be precisely defined. The method described in this paper tells us of the actual numbers of headlice in crops of hair on individual people. From it we may learn the proportion of people who are infested at different times or places, and the number of lice on different people: also the proportion of males, females and young in the louse population. The results with material from Woolwich and from Lagos are set out in this paper. Further work is now in progress on material received from several parts of the world: this material will be studied and the results published at a later date.

This paper is devoted to a critical analysis and revision of the systematics of the mammalian trypanosomes. It is shown that there is no justification for the recognition of more than one genus, Trypanosoma.

The trypanosomes are subdivided into two sections, each with distinct morphological and biological characteristics.

In the section corresponding to the lewisi group the method of reproduction is used as a criterion for the specific differentiation of the trypanosomes.

1. Examination of monthly quotas of Apodemus sylvaticus, Clethrionomys glareolus, and Microtus hirtus, for parasites over a period of 21 months, enabled the seasonal occurrence of Trombicula autumnalis larvae to be determined.

2. All three species are infested during the summer and autumn months, and Clethrionomys throughout the following winter and spring also. Shrews were not parasitised.

3. The mites occupy different positions on different hosts.

4. Clethrionomys and rabbits (Oryctolagus) are of importance in maintaining the stock of harvest mites on some areas in the south of England.

1. An English anautogenous race and three European strains of the autogenous race of Culex pipiens have been studied comparatively for 3 years under laboratory conditions.

2. Prolonged illumination has an activating influence on females of the anautogenous race, both hibernating and laboratory bred, and greatly stimulates gorging.

3. With the aid of artificial light during the winter months the anautogenous race has been kept breeding in the laboratory throughout the year for eleven generations without the occurrence of cyclical hibernation (asthenobiosis). Consequently it is suggested that the length of daylight may be a factor of importance in controlling the natural hibernation of females of this race.

4. Females of the English anautogenous race, whether of hibernating, or of active generations, laid normally after one blood meal and did not exhibit gonotrophic dissociation. They also oviposited readily after being artificially fed on bird blood.

5. Unfed females lived for a maximum of 19 days and never accumulated fat-body autotrophically.

6. Females, if fed on apple for 5 weeks, accumulated sufficient reserves to enable a small percentage of them to survive 15 weeks of starvation.

7. In the anautogenous race pairing always begins in the air although it may be completed on the ground. The females do not lay without a blood meal, and they show little tendency to bite man but bite birds voraciously.

8. Strains of the autogenous race of C. pipiens were obtained from rural areas in Greece, Malta and Hungary and have been maintained in the laboratory for over 3 years.

9. Continuous breeding under autogenous conditions (no blood meals) for several years and through forty-five to forty-nine generations has had no deleterious eflect on these autogenous strains.

10. Spanogyny, or the gradual decrease in the numbers of females produced in succeeding generations, does not necessarily follow prolonged autogeny if the cultures are kept under favourable conditions.

11. Males of the autogenous race pair with resting females, so that pairing can take place in very small areas.

12. Cross-mating was easily obtained between the two races, autogenous and anautogenous, in both directions: male autogenous + female anautogenous; and male anautogenous + female autogenous. Stenogamy and autogeny are hereditary characters. Stenogarny always appears in the F1 generation, but autogeny sometimes appears in the F1 generation and sometimes not until the F2 generation.

13. Eggs are quickly killed by temperatures below freezing-point; and young larvae die within 24 hours at 0° C. Adults, even hibernating females, die within 4 days at −16° C.

Through the kindness of H. H. Woken, the veterinary surgeon of the Zoological Garden in Leningrad, we were able to examine the faeces of two species of birds—the grey partridge (Perdix perdix) and the stone partridge (Caccabis chucar). It is very probable that the coccidian found by us is common to both species of birds, but as they were kept in the same cage it was not possible to determine the origin of the faeces examined.