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Show 10 DK. T. S. COBBOLD ON A NEW ENTOZOON. [Jan. 13, round worms in large numbers in the general serous cavity of the abdomen. Moreover there had to be taken into consideration the peculiarities of the digitigrade mammal thus infested, its comparative rarity, and also its limited area of geographical distribution, these several influences being unquestionably concerned in the " fixation," so to speak, of the specific form likely to be encountered. It is not surprising therefore that our anticipations in the above relation should have been more or less completely verified ; and accordingly it turns out that we here encounter a new genus of internal parasites offering peculiarities of structure, and apparently also of habit, which on the whole suggest a slight approximation to the ordinary filarine genera, on tbe one hand, but with a closer connexion with the remarkable genus Dracunculus on the other. When all the facts bearing upon the genetic relations of the Guinea-worm come to be fully known, it may then turn out that m y determinations, in respect of the affinities of the new worm, are somewhat wide of the mark ; but, in the meantime, the following data will show the grounds on which I have provisionally asserted this alliance. All the specimens received by me, thirty-four in number, were females ; therefore, in the absence of any knowledge of the corresponding male parasites, the following characters must be regarded as applicable only to one of the sexes :- Order NEMATODA, Rud. Suborder NEM. PROCTUCHA, Dies. Family FILARIDEA, Dies. Subfamily CHEILONEMIDIA, Dies. ACANTHOCHEILONEMA, g. n. Head furnished with three spinous lips; body filiform ; female endoparasitic in mammals. A. DRACUNCULOIDES, Sp. n. Body smooth, finely attenuated in front, uniformly thick below; head sharply pointed when the lips are closed, obtuse when exserted ; neck spirally twisted in four or five circles ; tail abruptly truncate, with a solitary, central, very slightly projecting lobe; no reproductive orifice visible. Length 1|" to 2_-"; general breadth fa" to -fa". This combined generic and specific description, though sufficient for future identifications, may, I think, be profitably supplemented by other particulars relating to size, external form, and general organization, amongst which I have remarked the following :-The head immediately beneath the insertion of the lips measures so little as the jfa-$" m diameter, whilst the neck proper gives only twice the same amount of thickness. The tail is fully fa" in breadth, its feebly pronounced central lobe being no more than the Y I U " wide at the base. The mature eggs, or those containing more or less per- |