This subject has already been considered in some of its aspects in the first part of this paper, but the methods which apply more especially to the study of the internal anatomy will now be dealt with.

The examination of a vast number of ticks, collected in late years from various hosts in many parts of the world, has resulted in the addition of several new species to the genus Haemaphysalis. Though only 13 of the species admitted by Neumann in his “Révision” (Pt. II, 1897) still stand, the number of recognised good species now reaches 43.

The observations here recorded relate to rat-fleas: (I) in Suffolk and North Essex, and (II) in Cambridgeshire.

It is only within the last half-dozen years that any serious attempt has been made to deal systematically with the parasitic worms of Australia. In 1909 Dr T. Harvey Johnston commenced what has proved to be a most extensive and successful survey of the cestode parasites. Dealing at first chiefly with Southern forms, he has latterly (1912) continued his investigations in Queensland and has extended them to include Nematodes and Echinorhynchs. Some years previously (1901) Dr S. J. Johnston of Sydney had started a study of the Trematode parasites, but this did not lead to any outstanding results until last year, when his important paper on the Trematode parasites of Australian frogs appeared. He has followed this up by another important work on Trematodes from North Queensland, which has appeared during the present year.

Two very curious cases of pseudo-parasitism have recently come before my notice :—

Towards the middle of last year some centipedes were forwarded to me which had been vomited and passed by a women of 68 years of age. Some of the centipedes emerged through the patient's nose, and it must be mentioned that she was also suffering from a round worm. One of her doctors was of opinion that the centipedes were certainly breeding inside the lady's intestine, and as many as seven or eight, sometimes more, were daily leaving the alimentary canal.

To summarize our principal observations made in the course of the investigation into the rat-fleas of the suspected plague area of East Suffolk, July—October, 1911:

(1) We found an average of four fleas per rat: 822 rats were examined and 3293 fleas taken.

(2) The average was subject to a local variation (0·6 to 6·5).

(3) 15 species of fleas were taken from the rats, but of these there were only two species, C. fasciatus and C. agyrtes, which occurred in any numbers.

There were C. fasciatus 1986 or about 60 per cent.

C. agyrtes 1257 or about 38 per cent.

Rare species 50 or about 2 per cent.

(4) The average number of fleas per rat and the percentage of rats infested by fleas showed a well-marked seasonal variation, there being a considerable decline in the numbers as the cooler weather came on. Ceratophyllus fasciatus and Ctenophthalmus agyrtes both participated in a similar way in this variation.

(5) C. fasciatus is chiefly found on rats caught near human habitations; C. agyrtes on those caught in the hedgerows.

The new species herein described are of interest, although we can only deal with females, as is so frequently the case with this genus. One species (I. kempi), allied to the North American I. angustus, comes from a hitherto unexplored region on the north-east frontier of India, having been collected by the Abor Expedition. Two species (I. daveyi and I. oldi) are from Africa, and offer a peculiarity of structure in that they possess anal grooves having the form of a horse-shoe, an appearance only hitherto observed in three other species of Ixodes, all of which are African. The fourth species (I. ricinoides) is from China, and is allied to our I. ricinus:

Agrippina bona, a gregarine parasitic in the gut of the larva of the rat-flea Ceratophyllus fasciatus, was first described by Strickland in 1912. His account of the sporulation of the gregarine was so curious that a more detailed investigation has been undertaken, which has given rise to the present paper. The work has been done in the Quick Laboratory, under Professor Nuttall, to whom I wish to express my thanks for the interest he has taken in my researches, and for his constant encouragement.

The present investigation was primarily undertaken by Mr G. Merriman at the suggestion of Professor Nuttall, but was discontinued at a very early stage owing to Mr Merriman's departure for Africa. The object of the investigation was:

(1) To determine if immature stages of ticks whose mouth-parts have been mutilated or torn off by the forcible removal of the parasite from the host possess the power of regeneration. In nature, many immature ticks must be injured in this manner, and it seemed of interest to determine if they could regenerate the lost parts, thus helping them in the struggle for existence.

(2) To determine if the small legs occasionally observed in nymphal and adult ticks are due to mechanical injury followed by regeneration. A very striking example of such a tick is the type specimen of Amblyomma scaevola Oudemanns (♂), in which four legs are markedly under-developed. In the large quantity of tick material that has been received at the Quick Laboratory, individuals with one or more miniature legs have been observed repeatedly.

The virus of rinderpest is present in the blood and all the body-fluids during the febrile period. In the blood it is so plentiful that the inoculation of a single drop of a 1 in 10,000 dilution is said to be sufficient to infect a calf. According to Nicolle and Adil Bey the causal agent is filterable, and therefore is supposed to be ultra-microscopic. Direct examination of fresh specimens reveals nothing parasitic, nor has anything of the kind been shown by various methods of staining of dried films.

The following record relates to fleas collected from rats in and about Cambridge during the period 3rd March, 1909, to 20th November, 1911. We had difficulty in obtaining rats in Cambridge during the year 1911 owing largely to the high price asked by professional rat-catchers who usually sell them for sporting purposes. We have, consequently, included data collected by us during the two years before this investigation was undertaken on behalf of the Local Government Board.

Aragão (1912) has recently described a new species of tick which he raised through three complete generations upon cold-blooded animals, the natural hosts in Brazil. He gave the species the name Amblyomma agamum because reproduction occurred parthenogenetically, males not having as yet been observed. The tick, in common with most other Ixodidae, feeds upon three successive hosts in the larval, nymphal and adult stages; it may, however, undergo metamorphosis from larva to nymph upon the host. This observation of Aragão's is the first of the kind, for parthenogenesis has not hitherto been observed in ticks. In the course of his raising experiments he obtained thousands of females which laid fertile eggs in the absence of males.

The importance of the Argasidae, in relation to the transmission of disease, has suggested the need of a moderately detailed description of the anatomy of an example of the family. With the object of supplying this want, the authors have made a study of a widely distributed species—Argas persicus—and they venture to hope that the work embodied in the following pages will furnish something towards the much-needed information, the present lack of which adds to the many difficulties which are encountered in investigations concerning the life-stages of pathogenic Haematozoa.

During the course of the last few years our knowledge of parasitic worms in all their various relations has advanced and increased to a very considerable and satisfactory extent. From the purely zoological point of view the advances have been of the highest order, many important discoveries having been made, not only in connection with the morphology but also, and particularly, in connection with the development and bionomics of these worms. At the same time there has been a steadily increasing improvement in our ideas of their classification and relationships which has resulted in a much wider and more accurate conception of their zoological nature. While these rapidly accumulating discoveries have greatly extended the knowledge at our disposal, they have, in addition, rendered such facts easier of study and of use, with the result that the economic value of the subject as a whole has been very materially enhanced. Helminthology shares with Protozoology and Entomology the, in some respects, unenviable distinction of being of intrinsic importance not only to medicine, but also to veterinary and agricultural science. It has a smaller but no less definite economic importance in relation to fisheries. Apart from their purely zoological interest it is particularly as agents of disease that the parasitic worms are of importance, but there are a number of other matters connected with habits and distribution, on which a study of parasites may throw considerable light.

This brief note is the result of a series of examinations of blood-films of various mammals and was suggested by Dr Braddon's interesting paper, the manuscript of which I had an opportunity of reading while working in the Quick Laboratory, Cambridge1.

Prof. Nuttall has suggested that I should continue his investigations (1913) on variation in size and structure due to nutrition, using other species of Rhipicephalus and species of other genera.

In November 1912, through the courtesy of Mr S. W. J. Scholefield, Prof. Nuttall received fourteen living nymphs of Argas brumpti from Kitui, British East Africa. As only the adults and later stage nymphs of this species are known, an attempt was made to raise the species in the laboratory.

The ornamentation so characteristic in Amblyomma, Aponomma, Dermacentor, and occasionally met with in species of Rhipicephalus and Hyalomma, is of use to the systematist in the differentiation of species. In many descriptions of ornate Ixodidae the colours are referred to as “metallic” owing to the sheen they possess when the ticks are preserved in alcohol.

Among other cestodes collected by me some years ago were specimens of the prismatic malformation of a tape-worm which I have recently examined. This abnormality in the taenioid group of cestodes has been frequently reported in Europe, especially in Taenia saginata, since Andry's case was first described in 1700. This malformation is known as Taenia ‘tridre,’ ‘triquestre,’ or ‘prismatique’ in French; as ‘dreikantige’ in German, and as ‘tri-radiate’ or ‘prismatic’ in English. But as far as my knowledge goes, we do not find a full description of any such abnormality in Taenia crassicollis, though a brief description of it was given by Bremser in 1819 and 1824. It is now recorded for the first time from Japan.

No group of ticks presents a more interesting biological study than the genus Dermacentor. The diversity of habits of these ticks is remarkable. These differences in habits, especially when we find them correlated with certain structural characteristics, would lead some to consider splitting the genus into two or more genera or subgenera. This we do not think well advised.