1. During the free-living development the larvæ of Triodontophorus tenuicollis undergo two moults separating three larval stages, the last stage remaining ensheathed in the cuticule of the previous stage.

2. The development takes about four days when the eggs are cultured in horse fæces and charcoal at 26° C.

3. The infective or third stage larvæ are climbers, and also show a marked resistance to desiccation ; they can also withstand variations in temperature from – 8° C. to 60° C.

4. They do not penetrate skin.

5. Infection of the host is probably via the mouth during grazing.

6. The fourth-stage larva is described. It is free in the lumen of the colon, possesses a well-marked larval buccal capsule and three stout and pointed œsophageal teeth. Sex differences are now present.

7. The adult buccal capsule develops in the form of a vesicle round the base of the larval buccal capsule.

8. The probable mode of its parasitic development is given.

9. A fourth-stage larva, probably that of either T. brevicauda or T. serratus, is described.

The specimens here described were contained in cysts from the heart of a Bushbuck (Tragelaphus sylvaticus) submitted for examination by A. J. Stent, Esq., of the Vizara Rubber Plantation, Nyasaland Similar lesions have been reported by others from the heart of the Kudu (Strepsiceros kudu) in the same region, but no opportunity of examining these has occurred.

Our present knowledge of the Strongylid parasites of reptiles is based primarily on Dujardin (1845), who refers all the forms along with those of other vertebrates under a common genus Strongylus, and described four species from the reptilian hosts. Since then our knowledge of parasitic fauna has considerably increased, and von Linstow (1878–89) gave an enlarged list under the same genus from reptiles and also a few under the genus Kalicephalus, Later, with improved methods of Nematode study the forms described were revised, and it was found necessary to split the genus Strongylus, and several groups of a diverse character were recognised. The genus Strongylus was thus split up into several genera, and some of them were removed from the family Strongylidæ. The form Strongylus dispar of Dujardin from the Anguis fragilis was removed into a separate genus, Oswaldocruzia and Strongylus auricularis, with its characters in the absence of buccal capsule and the bifid and trifid distal ends of the spicule seemed more closely allied to Trichostrongylidæ Leiper, and was also removed to the genus Oswaldocruzia.

The genus Mesocestoides was created in 1863 by Vaillant to receive a new species of cestode found by him in Viverra genetta and named M. ambiguus. Unfortunately, the description of this form is such that, although the generic characters can be recognised, it is impossible to say to which of the several species found in mammals it should be referred, and therefore Fuhrmann (1908) regarded it as a species inquirenda. Weiss (1910), in redescribing a form of Mesocestoides from the same host, gives no details which would enable the parasite to be distinguished from the other members of the genus. He notes that his form is only 50 mm. long, while that described by Vaillant was 160 to 240 mm. long. However, as Neumann (1896) points out, M. lineatus has a size varying between 30 and 250 mm. The size of M. ambiguus therefore is only of use in showing that it does not belong to the species M. bassarisci or M. cæstus referred to later in this paper. It still leaves its identity a matter of speculation as, in addition to M. lineatus, M. mesorchis has dimensions which fall within these limits.

In a varied collection of parasitic worms sent by Dr. G. M. Heydon, of Raboul, New Guinea, to Prof. R. T. Leiper, Director of this Institute, there were a number of specimens of Œsophagostomum dentatum which had been taken from the large intestine of a pig. An accompanying letter stated that the pigs at Roboul are crossbred between the local wild pig and European breeds.