1. The structure of the proboscides of the larva of Dibothriorhynchus grossum (Rud.) is described. Each proboscis is provided with four sets of extrinsic muscles, and there is an anterior dorso-ventral muscle mass connected to all four proboscides.

2. The musculature of the body and scolex is described.

3. The nervous system consists of a brain, two lateral nerve cords, two outer and inner anterior nerves on each side, twenty-five pairs of bothridial nerves to each bothridium, four longitudinal bothridial nerves connecting these latter before their entry into the bothridia, four proboscis nerves arising from the brain, and a series of lateral nerves supplying the lateral regions of the body.

4. The so-called ganglia contain no nerve cells, these are present only in the posterior median commissure which is therefore the nerve centre.

1. Rana clamitans of New York and R. pipiens from the middle part of the United States, were found to be infected by a Myxosporidian, apparently identical with Leptotheca ohlmacheri (Gurley) Labbé, found by Ohlmacher in the kidney of Bufo lentiginosus.

2. The Myxosporidian was found only in the space between Bowman's capsule and the glomerulus of the Malpighian body and in the uriniferous tubules of the kidneys of the host, no other organ being infected.

3. The mature spore contains two independent uninucleate sporoplasms which fuse into one prior to the germination in the posterior region of the stomach or duodenum of a new host.

4. The germination of the spore was observed in hanging drop preparations with the digestive fluid.

5. The youngest stage found in the lumen of the tubule of the kidney, was the uninucleate form.

6. The trophozoites multiply actively by a process of gemmation and probably also by a schizogony of the uninucleate forms.

7. The trophozoites are, as a rule, disporous and the spores develop independently of each other.

8. The vegetative nucleus persists throughout the entire trophic life of the individual.

9. The Myxosporidian does not exercise any fatal effect upon the host.

10. Infection takes place through the mouth. The liberated binucleate amoebulae probably penetrate through the wall of the small intestine, reach the coelom and are carried to the uriniferous tubules through the nephrostomes or blood vessels.

This contribution is intended to be the last of this series. As one who may claim to have revived interest in these crustaceans from this region since the days of Bassett-Smith just prior to the beginning of the century, I find it particularly gratifying that several Indian zoologists are now steadily engaged in adding to our knowledge of these forms. Altogether some forty-three genera containing about 120 species have now been recorded from the Indian Ocean. This must form only a small fraction of the total number of forms that actually occur on the wide variety of hosts inhabiting this region.

An investigation of the carbohydrate energy metabolism of Rhabdias bufonis, the lung-dwelling nematode parasite of the African toad, Bufo regularis, indicates that the nematode stores very little glycogen (0·137 ± 0·003% on a fresh weight basis) but does utilize oxygen in vitro. The intracellular distribution and high levels of activity observed for the enzymes phosphoenolpyruvate carboxykinase, pyruvate kinase, lactate dehydrogenase, malate dehydrogenase, malic enzyme and fumarate reductase suggest two alternative pathways of carbohydrate energy metabolism.

In order to investigate the mode of action of a new class of schistosomicides, the N-alkylaminoalkanethiosulphuric acids, the ‘outer 35S] 2-[(1-methylpropyl)amino]-1-octanethiosulphuric acid was synthesized. Labelling studies of adult Schistosoma mansoni were performed in infected mice and in in vitro incubations. After a single oral dose of the drug to infected mice, 5 metabolites were detected by thin-layer chromatography in organic extracts of male and female adult schistosomes. In vitro studies showed that the same compounds were present in organic extracts obtained from adult male and female worms. One of these metabolites was identified by mass spectroscopy as being the dimeric disulphide derivative of the parent labelled thiosulphuric acid.

The helminth community in the digestive tract of the sedentary predatory fish, Sciaena umbra, near the Scandola Nature Reserve, Corsica, consists of 5 species of digeneans. Anoiktostoma coronatum (in the rectum) and Metadena pauli (in the intestine) were found in almost all the fish, and in high numbers; they are considered core species. Distomum aloysiae, Pleorchis polyorchis (both in the intestine), and Stephanostomum bicoronatum (in the rectum) were relatively uncommon, usually found in small numbers, and are considered satellite species. The two core species were very abundant in June, when the size of their populations was strongly correlated with the size of the host fish. At this time, M. pauli was found mainly in the duodenum, but in high populations was spread throughout the intestine (s. strict.). Both species were much less abundant in October, their populations were less dependent on host size, and M. pauli was more limited to the anterior intestine. Pleorchis polyorchis and Distomum aloysiae were more frequent in October, were found predominately in fish with few M. pauli, and were found posterior to M. pauli, suggesting some interactions between these species. Stephano-stomum bicoronatum showed no seasonal patterns, and no apparent interactions with A. coronatum.

We compared a Trypanosoma cruzi clone unable to infect or induce pathology in mice (CL-14), with virulent T. cruzi (Y and CL strains) in terms of cruzipain expression, subcellular distribution and functional activity. Our results showed that (1) intracellular Y amastigotes expressed R1 (carboxy-terminal) and R2 (catalytic) domains concentrated in cytoplasmic vesicles, while CL-14 presented R1 labelling on membrane clusters and R2 in intracellular compartments, (2) CL-14-trypomastigotes presented R1 and R2 staining preferentially on flagellar and cellular membranes, similar to CL, but different from Y strain intracellular labelling pattern, (3) flow-cytometry revealed higher expression of R1 by CL-14-trypomastigotes than virulent strains, but R2 staining similar to CL-trypomastigotes, (4) CL-14-trypomastigotes presented normal cruzipain activity in gelatin gels, but different banding patterns were found in CL-14 versus CL and Y strains. Our data rule out failure in cruzipain expression, activity or subcellular distribution as an explanation for CL-14 biological behaviour, but suggest the expression of a different isoform. These results also cast doubt on the putative role of cruzipain as a target of immunopathological responses, since high levels of functional cruzipain are expressed by a non-pathogenic T. cruzi.

Angiostrongylus cantonensis is a parasitic nematode known to infect humans through the ingestion of third stage larvae which can cause inflammation and damage to the central nervous system. Currently, polymerase chain reaction (PCR) is one of the most reliable diagnostic methods for detecting A. cantonensis in humans as well as in gastropod hosts, but requires expensive and specialized equipment. Here, we compare the sensitivity and accuracy of a recombinase polymerase amplification Exo (RPA-EXO) assay, and a recombinase polymerase amplification lateral flow assay (RPA-LFA) with a traditional quantitative PCR (qPCR) assay currently available. The three assays were used to test 35 slugs from Hawai‘i for the presence of A. cantonensis DNA. Consistent results among the three tests were shown in 23/35 samples (65.7%), while 7/35 (20%) were discordant in low infection level samples (<0.01 larvae per mg tissue), and 5/35 (14.3%) were equivocal. To evaluate sensitivity, a partial ITS1 gene was cloned, and serial plasmid dilutions were created ranging from 100 copies μL−1 to ~1 copy μL−1. All three assays consistently detected 50–100 copies μL−1 in triplicate and qPCR was able to detect ~13 copies μL−1 in triplicate. RPA-EXO was able to detect 25 copies μL−1 in triplicate and RPA-LFA was not able to amplify consistently below 50 copies μL−1. Thus, our RPA-EXO and RPA-LFA assays do not appear as sensitive as the current qPCR assay at low DNA concentrations; however, these tests have numerous advantages that may make them useful alternatives to qPCR.

Cryptosporidium parvum are protozoan parasites responsible for outbreaks of gastrointestinal disease worldwide. Within the apical complex of this organism reside numerous vesicular secretory organelles and their discharge has been identified as essential for sporozoite motility, cell attachment and penetration. Traditionally, investigation of apical organelle discharge has relied on microscopic and immunochemical hybridization techniques. In this study we demonstrate for the first time how flow cytometry, in combination with vital dye staining, provides an avenue for discrimination of distinct physiological events occurring within Cryptosporidium sporozoites post-excystation. Time-course studies of freshly excysted sporozoites were carried out at 37°C in cell-free medium, stained with the fluorescent dyes SYTO9/PI, DiBAC4(3), Fluo-4 AM or FM1-43 and analysed by flow cytometry. Significant decreases in sporozoite plasma membrane permeability and increased membrane depolarization were found to be accompanied by concomitant increases in intracellular calcium. Subsequent to these changes, large increases in exocytosed vesicular membrane were apparent. In addition, by measuring side and forward angle light scatter we were able to assess changes in internal granularity and size of sporozoites post-excystation. These observations were suggestive of rapid mobilization, utilization and discharge of apical organelles within sporozoites, which we relate to changes in sporozoite infectivity, ATP levels and total secreted soluble protein.

1. Three new species of eugregarine are described from the mid-gut of the larva of Costelytra zealandica (White).

2. Euspora zealandica occurs in the anterior region of the mid-gut near the gut caeca. Slictospora costelytrae occurs just posteriorly to E. zealandica. Euspora sp. occurs posteriorly to the malpighian tubules, but was found only rarely.

3. A description of the species and the life-cycle of two species are given.

4. The life-cycle of S. costelytrae takes about 8 weeks and that of E. zealandica 6 weeks.

5. Gametocysts will develop only at a humidity of 95–100 %.

6. The bi-associative species, E. zealandica, is more abundant in the 1st and 2nd instars than the large species, S. costelytrae. Both species are equally abundant in the 3rd instars, but the peak for incidence was in May for E. zealandica and June for S. costelytrae. This is related to the longer period of time taken for the life-history of S. costelytrae.

7. The incidence of gregarines builds up in each instar to over 90% then falls off, the time of fall off corresponding with the production of gametocysts which pass out with the faeces of the grub.

8. The gregarines mostly complete their cycle before the instars moult. This is borne out by the observation that cysts were not found in the smallest size group of each instar. There were many cases in the larger size group of all three instars where cysts only occurred.

9. Gametocysts are produced mainly in the autumn.

10. Gregarines were not found in grubs approaching metamorphosis (prepupae) nor in pupae nor adults.

11. It seems unlikely from the results that the gregarines have an adverse effect on the grubs as, in general, it was found that the larger grubs had the greater number of gregarines present, but further work on this is needed.

12. The life-history of the gregarines is closely correlated with the life-history of the beetle.

13. The presence of the gregarines only in the larval stages is related to the different habitat and behaviour of larva and adult.

I am grateful to the University Grants Committee for financial support.

Malaria microscopy in sub-Saharan Africa is often restricted by access to light microscopes. To address this gap, a novel portable inverted monocular microscope, the Newton Nm1, was designed and is now commercially available. Its diagnostic performance was assessed in a blinded-slide trial at ×1000 (oil) of Giemsa-stained thick blood films against a conventional microscope as undertaken by four Ugandan Ministry of Health technicians. With the Newton Nm1, diagnostic performance was: sensitivity 93·5% (95% confidence interval (CI) 78·6–99·2%), specificity 100·0% (95% CI 82·4–100·0%), positive predictive value 100·0% (95% CI 88·1–100·0%) and negative predictive value 90·5% (95% CI 69·6–98·8%). Discordance was due to a systematic error underestimating parasitaemia by ~45%; when counting Plasmodium parasites against 200 white blood cells, blood films with low parasitaemia (i.e. <100 μL−1 of blood) could be overlooked and misclassified. By contrast, specificity was excellent with no false positives encountered. Whilst proven useful, especially in resource-poor environments, it is still unclear how we can ensure the uptake of the Newton Nm1 within sub-Saharan Africa.

On Jan. 27th, 1920, among a number of nearly fully grown larvae of Bibiomarci which had been kept in the laboratory about two weeks, a few individuals were observed to be unhealthy or dead. These latter were found to contain parasitic Dipterous larvae, which eventually proved to be those of Hypocera incrassata Mg. Certain of these larvae were observed to be leaving the bodies of other larvae of Bibio marci at the same time.

Information relating to the characterization of cestode surface macromolecules is limited. This is especially the case with Taenia crassiceps, a well-recognized model for the study of larval cestodiasis. Here, the protein and glycoprotein composition of the tegumental surface and cyst fluid of the metacestode have been investigated using radio-isotope labelling, immunoprecipitation, SDS–PAGE and lectin affinity chromatography. A restricted number of surface proteins was labelled with the 125I/Iodogen method although the majority were immunogenic; in contrast an array of cyst fluid antigens were labelled. Host serum proteins, including immunoglobulins, were identified on the surface and in the cyst fluid. Some of the 125I-labelled surface proteins, including a 37 kDa molecule, have been shown to be glycoproteins and probably contain-D-mannose and/or D-glucose; there is limited or no N-acetylglucosamine and no terminal galactose present on these components. A 37 kDa surface molecule, possibly the same glycoprotein, was also precipitated by infection sera and this may endorse the theory that highly immunogenic carbohydrates are continuously shed by T. crassiceps as a mechanism for diverting the immune response of the host. Radio-iodinated and biosynthetically labelled T. crassiceps antigens were highly cross-reactive with antibody raised to other cestodes and not one antigen was identified as a possible candidate for use in specific immunodiagnosis of any of the important taeniid infections.

Taenia hydatigena cysticercosis is a widespread parasitic disease of wild and domestic animals. In Europe, the increase in wild boar population may potentially contribute to the spread of this parasitic infection. To determine the occurrence of cysticerci (metacestodes) in wild boar population from southern Italy, carcasses were inspected during three hunting seasons (2016–2018). Out of 3363 wild boar examined, 229 (6.8%) harboured cysticerci with 188 (82.1%) infected by a single cyst, vs 41 (17.9%) boars having more than one. Most of the positive animals (187; 81.7%) showed cysts on the liver, whereas a multiple localization of cysticerci was reported in 10 (4.4%) wild boar. The total number of cysts retrieved from positive animals was 301 (average 1.3). Molecular analysis revealed the occurrence of a common haplotype (Hap 8) shared between wild boar and domestic animals. Our findings suggest the presence of a T. hydatigena semi-domestic life cycle in which wild boar may play an important role, due to a large number of offal available to hunting dogs, wolves and foxes during hunting seasons. Hunters may be players in the management of wildlife species to control and prevent the circulation of parasitic diseases.

Homogenates of adult Schistosoma mansoni contain enzymes which are capable of transferring [14C]mannose from GDP[U-14C]mannose to a lipid acceptor which migrates as a single peak on a silica gel thin-layer plate. This lipid may belong to the class of polyprenol monophosphates which are intermediate elements in the glycosylation of nascent proteins. The schistosome mannosyl transferase activity is associated with membranous particles and is dependent on the presence of Mn2+. However, other divalent metals such as Mg2+ or Ca2+ can, in decreasing order of efficiency, replace Mn2+. When UDP[U-14C]glucose was incubated with the homogenates in the same conditions, relatively little label was transferred to the lipid acceptor. Live worms incubated in a medium containing GDP[U-14C]mannose seem to incorporate the label preferentially on the tegument and on adjacent subtegumental structures. By adding foetal calf serum to the medium, incorporation of the label can be stimulated.

Hepatic granulomas from mice infected with Schistosoma mansoni for periods of 8 weeks to 1 year were studied by electron microscopy. The different cell types present in the granulomas suggested that whilst a delayed hypersensitivity response predominated during early stages of infection an Arthus-type reaction associated with delayed hypersensi-tivity occurred at later stages of infection.

Monoclonal antibody 2A6 binds to the surface of the Dictyocaulus viviparus L3 sheath and identifies a molecule which is highly antigenic in both infected and vaccinated cattle. Immunogold electron microscopy reveals that the antibody binds to a highly stable surface coat overlying the epicuticle of the L3 sheath. The binding to the cuticular surface is stage specific, being restricted to the surface of the L3 sheath, although the antigen can be detected on Western blots of parasite homogenates from the L1 stage. Immunofluorescence on live parasites demonstrates that the antibodies also bind to the L3 sheath surface of many other strongylid nematodes. The antigen detected by 2A6 differs in molecular weight between the species; in D. viviparus the antigen is poorly resolved between 29 and 40 kDa by SDS-PAGE whereas in nematodes from the family Trichostrongyloidea a single band or doublet of approximately 20 kDa is detected, suggesting that a related molecule is present in these species. Although infection and vaccination with D. viviparus elicits a strong immune response to the L3 sheath antigen this does not appear to be the case following infection with other strongylid nematodes.

The description of one new species of Ascodipteron and another one of Nycteribosca is based on the material collected in Africa and Madagascar respectively by Mr H. Hoogstraal, of the United States Naval Medical Research Unit No. 3. These specimens represent a part of the collection which was sent to me for identification by Mr R. L. Wenzel of the Chicago Natural History Museum. In this paper I have also included the description of another new species of Ascodipteron of which two specimens were collected by Mr T. S. Jones in West Africa.

Specimens of Notocotylus attenuatus were examined in life and their ventral papillae studied by scanning and transmission electron microscopy. It was found that the papillae are non-secretory, very mobile and similar in ultrastructure to the papillae of other notocotylids previously described. Worms were removed from the host's caecum and the caecum surface examined where it had been in contact with the papillae; this revealed that the crypts in this region had been distorted and enlarged. It is suggested that the papillae serve to attach the worms to the distinct surface of the distal caecum by acting as hydraulically operated anchors working in conjunction with the lateral margins of the worm and allowing the oral sucker of this monostome fluke to be used for feeding.

During the period 1913–16, I conducted a Survey of the Agricultural Zoology of the Aberystwyth Area, for which purpose the University authorities received a grant from the Board of Agriculture. The area thus examined comprised N. Cardiganshire and some adjacent borders of Montgomeryshire, roughly about 250 sq. miles. It falls into three main physical divisions:

I. The mountainous upland (or high plateau) of solid rocks frequently covered by a considerable depth of peat. The rock succession is only irregularly exposed in deep stream cuttings, while these valleys are occupied by boulder clay and river deposits.

II. The surface of the coastal plateau shows exposures of rock and of boulder clay. The clay is usually exposed and rarely covered with peat.

III. The fall line, which is intermediate. Here the boulder clay generally follows the valleys, and it is usually covered with a thin layer of peat. Much of this is readily cut through by small streams.