I 



DR. T. S. COBBOLD ON ENTOZOA. 163 



in Lissotriton punctatus, not a single entozoon of any kind coiUd be obtained from 

 Triton cristatua; a fact rendered more significant inasmuch as the specimens were all 

 obtained from the same locality, namely from ponds at the summit of the Braid Hills 

 near Edinburgh. In the stomach of one of the large species there was a small trematode- 

 like body, but on microscopic examination it proved to be a young horse-leech. From 

 specimens of the lesser Newt, procured at intervals during the months of April, May and 

 June, 1855, there were obtained in the first place numerous examples of Ascaris acumi- 

 nata, the presence of which was by no means invariable; secondly, an abundance of 

 Ech'morhijnchua anthuris ; thirdly, multitudes of Opalina intestinalis, a ciliated infusorial 

 animalcule believed by Agassiz to be in reality only a larval planarian ; and fotu-thly, a 

 considerable number of Trichodince. The first three groups were found in the stomach 

 and duodenal portion of the intestinal canal ; the fourth occupying the cloaca and ducts 

 in its immediate neighbourhood. The only remark I have to offer respecting Ascaris 

 acwmmata has reference to its size, which is variously estimated by different authors ; 

 my specimens average about 8 Lines in length, which accords with Mr. Bellingham's 

 statement in his Catalogue of Irish Entozoa. This leads me further to observe, concern- 

 ing the definition of species, that much unnecessary stress is laid upon the relative size of 

 individuals, bulk alone, it would appear, being frequently regarded as a criterion of spe- 

 cific distinction. In very many instances at any rate it cannot be denied that this is the 

 case. I believe the error is so prevalent in the older lists, that for every new species 

 now added, two old ones might with propriety be expunged. In the present communica- 

 tion, it is not my intention to show how the truth of this assertion may be sustained by 

 an appeal to facts ; nevertheless, if it were desired, sufiicient illustration might be afforded 

 from the materials in hand. The second group, represented \)j Echinorhynchus anthuris 

 (figs. 54—62 inclusive), deserves attention, forming as that species does, on account of its small 

 size and extreme transparency, an excellent subject for microscopic investigation ; but a 

 minute description is not needed, in consequence of the admirable manner in which it was 

 originally described by its discoverer, M. Dujardin. General details being given in the de- 

 scription of the figures, attention in this place is only invited to a brief notice of the peculiar 

 ova. These characteristic bodies in their early state are perfectly roimd, appearing simply 

 as nucleated cellules in the interior of the so-called ovaries, which are also spherical, and 

 float loose in the cavity of the body; the nucleus may be taken to represent the germinal 

 vesicle, but it cannot be recognized in the fully developed ovum. In this latter condition 

 each ovum encloses a perfectly transparent ceU, lobed at both ends after the fashion 

 of Trichina, and an irregiilar but very distinctly granular yelk-Like mass ; these are 

 placed side by side; and from the granular body proceeds at either end a coiled 

 thread or chalaza advancing to the extremity of the external envelope and becoming 

 blended with it ; the wall of the transparent ceU exhibits in profile very deUcate un- 

 dulations. In regard to the infusorial Trichodina, which may yet turn out to be larval 

 forms of some higher group, I have only to observe that some were in the encysted con- 

 dition. 



Bothrops. — For an opportunity of dissecting a species of this genus I am indebted to 

 Mr. Edwards, Demonstrator of Anatomy in the University of Edinburgh. Several ex- 



VOL. XXII. z 



