Although several records now exist of the occurrence of Capillaria (Hepaticola) hepatica (Bancroft, 1893) as a natural infection of the wild rabbit the attempts which have been made to infect this host with eggs obtained from an infection in the rat have not been completely successful. Nishigori (1925) states that although this parasite can infect the rabbit and shew some development it does not reach maturity, while Saito (1925), in the English account of his paper given in The Japan Medical World states that “In the rabbit the larva might develop into maturity and cause pathological changes but do not multiply.”

Three species, and one variety, of the pseudophyllid genus Bothridium de Blainville, are known to occur in pythons. B. ovatum occurs in the African python (P. sebce): B. pythonis in the Indian python (P. molurus) and B. pythonis var minor in P. reticulatus, the Indo-Malayan python; while Maplestone and Southwell (1923, p. 317) record another species, B. ornatum from the Australasian python (P. spilotes var variegatus). The literature on this genus appears, so far, to have dealt only with morphology and taxonomies. Joyeux and Baer (1927, p. 126) describe the anatomy and relationships of B. ovatum, B. pythonis and B. pythonis var. minor. Braun (1894–1900, p. 1690) gives a brief description, accompanied by very detailed figures, of the anatomy of B. pythonis and also figures the embryonated ovum (pi. Iviii, fig. 8). This is the only figure of any developmental stage of the parasite which the writer has been able to discover. Southwell (1930, p. 58) records the worm from P. reticularis and P. molurus, in Bengal, Nepal and Ceylon, and summarises its anatomy. He also mentions its occurrence in a tiger which he thinks had been eating a python. No account of the life-cycle of any species of Bothridium appears to have been written. When, therefore, in February, 1932, some living Bothridium arrived in the Helminthology Department, it was resolved to discover how far its development resembled that of other better-known Psuedophyllids.

The purpose of the present paper is to bring together brief descriptions of the various species of the genus Anguillulina, more generally known under the synonymous generic name of Tylenchus Bastian, 1865. In the case of the plant-parasitic species, in addition to particulars on dimensions and morphology, data are given on life-history, hosts and geographical distribution; such matters as symptoms, pathology and methods of control are not dealt with.

Some preliminary experiments on the effects of potato root excretions in stimulating the larvæ of H. schachtii to hatch and emerge from the cyst, and the neutralisation of this stimulating factor by the root excretions of mustard seedlings, have already been described. Since chemical treatment of infected soil as a means of controlling the eelworm has been the subject of investigation in Europe for the past fifty years without yielding any results of practical value, investigations into the reactions of the paiasites to the root excretions of plants were undertaken in the hope that some result might be attained which would point to a solution of the eelworm problem on biological lines. The high degree of specialisation shown by the British potato-strain rendered it peculiary suitable for investigations of this character.