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XIV. — On Triclioclina as an Encloparasite. 

 By T. B. Eosseteb, F.E.M.S. 



{(had lUh October, 1886.) 

 Plate XVIII. 



I was led to the discovery of this Infusorian as an endoparasite by 

 a fortunate accident. Being anxious to find the habitat of an 

 endoparasite I had observed attached to the muscles of the larva of 

 Corethra jplvmicomis, whose life-history I was working out, I 

 selected the smooth water-newt as my subject, knowing from 

 observation of its habits that the newt feeds largely on these and 

 similar larvas ; but whilst dragging for them, I captured some 

 specimens of Triton cristatus, which I therefore included in my 

 investigations. 



Previous to experimenting with the larvae it was necessary to 

 ascertain what parasitic life the newt gave shelter to in its 

 alimentary canal, so that in tracing out the life-history of the 

 endoparasite of which the larva of Corethra is the host, the meta- 

 morphoses of one parasite might not be confounded with those of 

 another. 



It was during the dissection of one of the newts so obtained 

 that I observed in the fluid in which the viscera were placed, a 

 species of Triclioclina, resembling, but not, I think, identical 

 with, T. pediculus, which is so frequently found as an ectoparasite 

 on Hydra vulgaris in company with Kerona polyporum. The 

 creature was so named by Ehrenberg, a name which it still 

 retains with English naturalists, although it is known to Con- 

 tinental investigators under other names. Dujardin * places it 

 as the second genus in his family of Urceolarieae, naming it 

 Urceolaria stellina, but all writers agree in the fact of its being 

 ectoparasitic only, and free-swimming in its habits. Dujardin 

 says, " La face opposee garnie d'une couronne complete de cils, au 



EXPLANATION OF PLATE XVIII. 



Fig. 1.— Male organs of newt (after Owen), showing habitat of Trichodina. 

 a, testes, c, efferent tubes, e, kidney. /, uriuo-seminal canal, </, ureters. 



Fig. 2. — Trichodina sp. lateral view X 500. 



Fig. 3. — „ ventral view. 



Figs. 4 and 5. — Showing articulation of acetabulum (fig. 4 lorica, fi<>-. 5 

 acetabulum). 



Fig. 6. — Illustrating action of picro-carmine on the living subject, showing 

 lorica partially disintegrated, acetabulum detached, and ejected endoplasm. 



Fig. 7. — 'Trichodina in situ on Hydra (Saville Kent). 



* ' Histoire Naturclle des Zoophytes,' 1841, p. 527. 

 Scr. 2.— Vol. VI. 3 P 



