The life-history of Aggregata, eberthi is summarized in the accompanying diagram (Text-fig. 3). The stages shown above the dotted line occur in Sepia officinalis, those below in Portunus.

Merozoites (R), when swallowed by the cuttlefish, pass through the epithelium and enter the submucous tissue of the caecum or intestine, where they develop into young (undifferentiated) parasites (A) which grow into males (B) or females (E). The former, after undergoing repeated nuclear divisions (C), produce broods of microgametes (D)—each of which (D*) has a complicated structure. Females (E), on the other hand, are bodily converted into macrogametes (F), which undergo a complex series of nuclear changes during maturation. No reduction occurs during gametogenesis.

Fertilization (G) is effected by the union of one microgamete with one macrogamete, and is followed by the formation of a fertilization membrane which, in part, gives rise to the oocyst. The zygote (H) becomes a sporont, which, after repeated division of its nucleus (I, J), ultimately segments—leaving no residuum—into a large number of spherical uninucleate sporoblasts (K). Bach of these is then converted into a spore (L) containing three sporozoites and a small sporocystic residue.

The ripe spores pass out of the intestine with the cuttlefish's excrement; and when swallowed by a Portunus they open in its intestine and liberate their contained sporozoites (M). These penetrate the epithelium of the crab's midgut, and enter the subepithelial connective tissue, where they grow into schizonts (N, O). Finally, the schizonts undergo schizogony, producing large broods of merozoites (P, Q). No further development takes place unless the schizogonic cysts, in the crab's coelome, are eaten by a cuttlefish: in which case they liberate their contained merozoites (R) and the development just described then begins anew.

A. eberthi is, at every stage but one in the whole life-cycle, a haploid organism. Every nuclear division is mitotic: and every nucleus (except the zygote nucleus) contains a single set of six differentiated and unpaired chromosomes. In the zygote nucleus alone there are 12 chromosomes—six homologous pairs—derived from the two gamete nuclei: but at the first division of this nucleus (first division in sporont, Text-fig. 3, I) the chromosomes are again halved to six. Reduction (meiosis) thus occurs immediately after fertilization. No halving of the chromosome number occurs during gametogenesis or schizogony; and males, females, and asexual parasites all possess an identical chiomosomic constitution. Every nucleus in Text-fig. 3 is therefore an x nucleus, with the exception of stage H, which is 2x. (Between stages G and I many nuclear changes occur, but only one—the so-called “fertilization spindle”—is figured (H) in the diagram.)

While working on the amphistomes in the Congo Collection of the American Museum of Natural History, New York, it has been necessary to review the literature on this group of trematodes. In an earlier paper (1917), the writer described certain amphistomes from reptiles and birds and submitted an arrangement to show the probable relationship of the reptilian and avian amphistomes to those of other vertebrates. The amphistomes of fishes had been studied by Daday (1907), those of frogs by Cohn (1904) and Johnston (1912), while the mammalian species had been the subject of extensive papers by Fischoeder (1903) and Stiles and Goldberger (1910). Many of the descriptions were fragmentary, knowledge of the forms was incomplete, and the classification of Stiles and Goldberger was received with severe criticism, especially by Braun (1911), Odhner (1911) and Looss (1912). In this paper Looss described the lymphatic systems of Schizamphistomum scleroporum and Paramphistomum gigantocotyle, and announced (p. 358) that for many years he had been engaged in preparing a classification of the amphistomes which would be based on the form of the lymph and excretory systems and the structure of the copulatory apparatus.

The family Gnathostomidae contains several genera and a fair number of species of nematodes of rather aberrant type and of uncertain affinities. As pointed out by Baylis and Lane (1920) in their excellent revision of the family, there is little doubt but that it should be included in the superfamily Spiruroidea. The subfamily Gnathostominae is characterised by the possession of a head bulb containing four closed membranous hollow structures, called ballonets by Baylis and Lane, connected posteriorly with four elongate sac-like structures designated cervical sacs. Three genera are recognised in this sub-family as follows: Tanqua, in which the head bulb is provided with transverse cuticular ridges, and Echinocephalus and Gnathostoma in which the head bulb is provided with rows of thorn-like spines. In Echinocephalus the body is smooth and destitute of cuticular spines, whereas in Gnathostoma all or a large part of the body has rows of cuticular spines on the posterior edges of the annulations. The first two genera are parasitic in the intestinal tract of cold-blooded vertebrates, whereas Gnathostoma apparently has its normal habitat in the stomach wall of mammals, as Baylis and Lane have pointed out.

(A) Life History.

(1) Simulium larvae are found in streams where the current is very fast. They are sedentary in habit and fix themselves to some support by means of their posterior sucker and sticky salivary secretion.

(2) Progression is achieved by looping movements which have been described in detail.

(3) Larvae feed on all kinds of fresh water animalcules, and algae.

(4) Two species were reared from eggs to the adult flies for the first time in the laboratory. Abundance of food and aeration of water are two very important factors governing the rearing of these larvae.

(5) There are six larval stages, each stage lasting 4–7 days. The gradual changes in the successive stages are described in S. erythrocephalum and S. aureum.

(6) The sixth-stage larva, having woven its cocoon, changes into a pupa, the whole process, weaving of cocoon and pupation (described in detail), takes 75–90 minutes. Pupal life lasts 5–15 days, depending on temperature.

(7) The eggs are sub-triangular in form and are laid in large patches on aquatic plants below the surface of water.

(8) The first-stage larva is characterised by the presence of an egg-burster situated dorsally upon the head.

(B) Morphology.

(9) The larvae are eucephalous, with eleven faintly marked body-segments, three thoracic and eight abdominal, the eighth abdominal being apparently divided into two parts, the posterior carrying the anus and posterior sucker. There is a median uniramous thoracic proleg which like the posterior sucker is provided with a number of cuticular hooks.

(10) The head has a number of markings which are of great taxonomic importance.

(11) The head-appendages are: A pair of jointed antennae, a rounded labrum, a pair of lateral fan-shaped appendages (the premandibular organs), a pair of mandibles, a pair of maxillae each with a single-jointed palp, a hypopharynx, and a labium. These appendages have been described in detail in this paper for the first time.

(12) The alimentary canal, malpighian tubules, salivary glands, muscular system and gonads are dealt with in detail.

(13) The oesophageal valve has no blood sinus as has been erroneously described by previous writers.

(14) A pair of dorsal glands are present above the pharynx. Their walls consist of large uninuclear cells. Dorsal glands have so far been found only in Sciara among Dipterous larvae.

(15) There is a well-developed central as well as visceral nervous system. The bilobed brain lies in the head and a chain of eleven ganglia in the body. Both the supra-intestinal and the infra-intestinal visceral systems are fully worked out for the first time.

(16) There is a well-developed tracheal system with ten closed spiracles, one prothoracic, one metathoracic and eight abdominal.

(17) The flattened dorsal vessel stretches from the seventh abdominal segment to the head where it ends just behind the brain. It is dilated in the seventh segment to form the heart which is provided with two pairs of ostia.

(18) Nephrocytes or excretory cells (pericardial, and peri-oesophageal) are described for the first time and compared to similar structures in other Dipterous larvae.

(19) A detailed description of the early stages of all the known (seventeen)1 British species is given, with remarks about eleven of them, as they occur in Sweden, Norway and France.

(20) The characters used for determining the species are as follows: Larva. Head markings; antennae; mandibles; submentum; anal gills; ventral papillae; and posterior sucker. Pupa. Chaetotaxy, Respiratory filaments, and Cocoon.

When La Rue (1914 a) published his exhaustive monograph on the Proteocephalidae, all the then-known species of this family were, with one exception, shown to be very much alike. To substantiate this statement it will suffice to mention that all the six genera, into which La Rue grouped the species, were chiefly based upon trivial characters of the scolex and the distribution of the testes. The one exception referred to was the species which he re-named Monticellia coryphicephala (Monticelli), and this species differed from all the others in the remarkable and relatively deep-seated character of its principal genital organs being situated in the cortical region of the parenchyma instead of in the medullary. This one exception was promptly transferred by La Rue to a distinct new family, the Monticellidae, and the consequence was that he was still left dependent upon the aforesaid trivial characters as bases for his genera in the original family. Since 1914 however we have come to know of some other Proteocephalids exhibiting similar deep-seated differences of structure, and we are therefore in a position to re-consider the classification of the Proteocephalidae on broader lines, including Monticellia coryphicephala in that family. The general scheme of this re-classification I have already outlined in a paper (Woodland, 1925 a) which will be published either before or shortly after the present communication, and it is my purpose, in this latter, to justify the suggestions there referred to by discussing the subject in some detail. Before attempting this, however, I shall describe the structure of three new Proteocephalids, two from India (in a frog and a Varanid lizard) and one from the Sudan (in a Siluroid fish).

There are no published records of the occurrence of Acanthocephala in the vertebrates of Japan. Professor Seitaro Goto has very kindly sent me a small collection of these worms for identification. While the collection is not extensive, it seems worth while to publish the results of the investigation, especially since there are several new species and a considerable amount of new biological data. In the ten vials of materials contained in this consignment, but seven host species are represented. Four of these are amphibians, two are fishes, and one is a whale. The parasites which these harboured include four new species of the genus Acanthocephalus, a previously undescribed member of the genus Arhythmorhynchus, a species of the genus Echinorhynchus and one unidentified species each in the genera Bolbosoma and Centrorhynchus.

Habitat and Record. During November 1924, by the courtesy of Seizo Takeda, I received from the Yogyo Shikenjyo (Piscicultural Experiment Station) at Kitajima near Toyohashi, Japan, the head of a small Japanese eel, Anguilla japonica, whose buccal cavity appeared to be completely filled with about forty parasites belonging to the genus usually known as Lernaeocera, but to which Wilson (1917, p. 3) has given reasons for restoring the name Lernaea Linnaeus. (See Note, p. 251.)

Edward Alfred Minchin, M.A., F.R.S., will always be remembered as the first great British protozoologist. He may be said, indeed, to have founded the British School in this important subject and he was, during that period of his life which he devoted to it, outstandingly the leader. A special tribute to his memory, therefore, may most fittingly be paid in this Journal.

This worm was obtained from the intestine of Sarcogrammus indicus Stoliczka at Nagpur, C.P., India. It was flattened out between two glass slides, fixed in Mann's fluid and stained with Delafield's haematoxylin. The measurements of the worm given in the following description relate to the flattened specimen.

The genus Apelma was erected by Kieffer (1919) for the inclusion of two European species, of which he had males only. The characters upon which he laid stress, and by which he separated the genus from Forcipomyia, were the length of the claws and the absence of an empodium. Nothing is known of the early stages of these two species. Subsequently, Ingram and Macfie (1923) described an African species from three males reared by Bacot from larvae in the leaf axils of Dracaena sp. The early stages of this species were not preserved.

N. A. Cholodkovsky was born on the 4th of March 1858 at Irkutsk, Siberia, where his father was a physician. He attended school in St Petersburg (now Leningrad) and at the age of 17 entered the Academy of Medicine. After completing his medical education, having no inclination for practice, he joined the University and in 1885 obtained the lectureship of Zoology in the Institute of Forestry.

It would appear from casual references in literature that the seals and their relatives are quite commonly infested with certain mites which occur in the nasal passages or even in the bronchial tubes. Although there are several such references, apparently in but three have the mites been named. In these three cases they have been referred to the Gamasid (or Dermanyssid) genus Halarachne. The first species, Halarachne halichoeri Allman, from Halichoerus gryphus, an Atlantic seal, was described in 1847; the second, H. americana Banks, from Monarchus tropicalis, which is also an Atlantic species, was described in 1896; the third, H. otariae Steding, from Otaria californica (which is known to American mammalogists as Zalophus cali-fornianus), was described in 1923. The specimens upon which this last species was based were obtained in Germany, although the host is a native of the west coast of North America.

Infection experiments with Sarcoptes of cattle conducted upon a horse, two sheep, two rabbits, two rats, a cat and a man gave negative results. Active stages of the mite kept damp in the refrigerator lived 11 days, at room-temperature they lived 7 days, at 37° C. they lived 3 days, these being maximum periods observed. Eggs kept 5 days and over in the refrigerator subsequently failed to hatch when warmed; when kept at room-temperature they lived 16 days and hatched on being warmed; at 37°C. they survived 7 days.

Infection experiments with Psoroptes of cattle conducted upon one heifer gave negative results.

Chorioptes of cattle kept at room-temperature and protected from light survived 29 days.

Owing to the courtesy of Docent W. Stefanski, University of Warsaw, I have had the opportunity of studying some Nematoda collected by him from the large intestine of an elephant which died hi the Warsaw Circus.

In the course of the examination of the contents of the paunch and rumen of 70 Ruminants a Ciliate of an interesting type has been met with on eight occasions. It is surprising that a new form should be found in this situation as a number of workers seem to have devoted no little time to researches on the fauna of the ruminant stomach. One cannot think that this animal is to be found only in England, and we are driven to the conclusion that it must have been overlooked up to the present. As the organism is relatively small for a Ciliate and of a rather transparent appearance this is understandable, especially because it is rarely abundantly present. Although it has been found eight times, yet in a coverslip preparation where there will be several specimens of the other Ciliates in every field of the microscope, there may not be more than one or two specimens of this new form.

The object of the enquiry reported on below was to determine, if possible, the method of infection of Lucilia caesar, L. with Herpetomonas luciliae, a common parasite of the alimentary tract of the fly, the subject being not too remote from the kalaazar problem to lack interest.

The various suggestions concerning the mode of spreading of Monocystid Gregarines parasitic in earthworms have been already summarised by Minchin (1903), Hesse (1909) and more recently by Bhatia (1924). The last named author seemed to find that the spores from the vesicula seminalis may escape during copulation with the seminal fluid, may be transferred to the receptacula seminis to appear finally inside the cocoon of the earthworm. This observation has led him to suppose that the earthworm may become infected before it emerges from the cocoon. He does not, however, consider this mode of infection as the principal one, but accepts the general view that the majority of spores are set free only after the death of the worm and the complete disintegration of its body.

Adults of the family Simuliidae have been known in Europe for a very long time as very serious pests affecting both men and cattle, and there were many interesting legends, even up to the middle of the eighteenth century, explaining their origin from grottos in the mountains (Tömösváry). Fabricius (1784) for the first time found a Simulium pupa (probably that of S. venustum Say) and described it under the name Tipula sericea, but to Schönbauer (1795) we owe the discovery that the earlier stages (egg, larva and pupa) of Simulium (Kolumbatczer-Mücke) are to be found in running water.