930 Transactions of the Society. 



moyen desquels l'animal nage librement ou niarche a la surface des 

 Hydras." Saville Kent, in his ' Manual of the Infusoria,' p. 646, 

 retains the name of Trichodina pediculus, and, under habitat, 

 distinctly classes it as an ectoparasite, referring also to a new 

 habitat, on the branchial appendages of lame of Triton cristatus. 

 This I am able to confirm, having found them this year in the 

 same place on larvae of Triton. These Trichodina, which are 

 ectoparasitic on the branchiae of the larva of Triton, retain their 

 affinity for Hydra vidgaris, as can be proved by taking some from 

 a larva of Triton whose branchiae are infested with them, and 

 placing them in a watchglass with Hydra, when they will be seen 

 to attach themselves by their acetabulum to the surface of the 

 tentacles of the llydrve. 



I have searched carefully to discover if these Trichodina are 

 ectoparasitic on either the adult triton or newt, but have been 

 unsuccessful, although I have captured both in company with 

 larvae, whose branchiae have been infested with them. 



In order to trace the origin of the Trichodina which, as I have 

 said, I found accidentally, I determined in March of the present 

 year to investigate the matter systematically, and accordingly I 

 killed a male specimen of Triton cristatus with chloroform, washed 

 it with warm water with a camel's hair brush, opened it ventrally, 

 and extracted the viscera. These were placed in a\vatchglass with 

 distilled water, when numbers of Trichodina were observed with a 

 1 in. objective in the fluid; some were taken up with a pipette, 

 placed on a glass plate, covered with a cover-glass, and carefully 

 compared with the figures of T. pedicidus in Saville Kent's ' Infu- 

 soria,' which they were found closely to resemble. A female Triton 

 was next taken, and subjected to the same process, but proved a 

 failure. A male smooth water-newt was treated in the same way, 

 and yielded an abundant supply ; but a female newt from the 

 same source was barren of results. These preliminary observations 

 furnished sufficient evidence that the Trichodina did exist in the 

 viscera as endoparasites, and I may say that great caution was 

 exercised in regard to the cleanliness of the troughs, pipettes, and 

 dissecting instruments that were used. 



On the 18th of June I captured some newts, and entered upon 

 a still more thorough investigation of the subject. 



A small newt was killed with chloroform, washed in warm 

 water, afterwards in distilled water, and then placed in an oblong 

 glass trough. The lower jaw was removed, and the ventral side 

 opened from thorax to anus — a slit being made on either side to 

 allow the dermis to be thrown back, and thus expose the whole of 

 the viscera. The heart, lungs, and liver, with the gall-bladder, 

 Avere detached and placed on glass plates and covered with small 

 bell-glasses. Each was separately examined, at first dry as an 



