_Tænia nana_, Siebold.--As regards the dwarf tapeworm, unless Spooner’s case be genuine, there is but one solitary instance on record of its occurrence in the human body; moreover, we have no evidence of its having existed in any other host. It was discovered by Dr Bilharz, of Cairo, at the post-mortem examination of a boy who died from inflammation of the cerebral membranes. Prodigious numbers existed. The largest specimen measured only one inch in length. To the naked eye these worms resemble short threads, and consequently they might very readily be overlooked. The head is broad and furnished with a formidable rostellum armed with a crown of hooks. These hooks have large anterior root-processes, which, extending unusually forward, impart to the individual hooks a bifid character. By far the best account of this worm is furnished by Leuckart, to whom I am indebted for a specimen. BIBLIOGRAPHY (No. 17).--_Cobbold_, ‘Entozoa,’ p. 244.--_Davaine_ (l. c., Bibl. No. 2), p. 574.--_Heller_, l. c., s. 606.--_Küchenmeister_, l. c., Eng. edit., p. 141.--_Leuckart_, l. c., Bd. i, s. 393.--_Von Siebold_ and _Bilharz_, in Von Sieb. and Köll. Zeitschr., Bd. iv.--_Spooner_, ‘Amer. Journ. Med. Sci.,’ 1873.--_Van Beneden_, ‘Iconographie,’ l. c., pl. iii, fig. 17.--_Weinland, ‘Diplacanthus nanus,’_ l. c., p. 85. _Tænia Madagascariensis_, Davaine.--This appears to be a well-defined species although the head has not yet been seen. It probably forms the type of a distinct genus. Dr Grenet, stationed at Mayotte (Comores), twice encountered single specimens passed by two young children, eighteen and twenty-four months of age respectively. The proglottides have their genital pores uniserially arranged, and they show, in their interior, remarkable egg-capsules, from 120 to 150 in number in all, each containing from 300 to 400 eggs. These give a long diameter of 1/625″ for the outer envelope and 1/1250″ for the inner, or shell proper. The embryo measures only the 1/2500 of an inch. A full account of this parasite, with figures, is given by Davaine (‘Les Cestoïdes,’ l. c., Bibl. No. 2, p. 577 _et seq._). _Tænia marginata_, Batsch.--Although I possess no certain evidence of the occurrence of this parasite in its adult condition in the human bearer, yet there is a tapeworm in the Edinburgh Anatomical Museum referable to this species, which was said to have been obtained from the human body. This worm is very common in the dog. The principal evidence demonstrating the occurrence of the larval representative of this species (_Cysticercus tenuicollis_) in man, rests upon the two cases recorded in Schleissner’s ‘Nosography’ of Iceland. One of the alleged instances, however, has been proved by Küchenmeister and Krabbe to be that of an echinococcus; so that, after all, there only remains the solitary case observed by Schleissner himself, in which the parasite can fairly be considered as the “slender-necked hydatid.”