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On the Zoological Position of Dysteria. 

 By P. H. GossE, F.R.S. 



During my stay at Tenby last summer^ I had some oppor- 

 tunities of studying the new and singular animal Dysteria, 

 the subject of Professor Huxley's excellent memoir in the 

 January number of the ' Quarterly Journal.' While I can- 

 not but admire the skill with which he has worked out the 

 interior structure^ some parts of which presented to my own 

 investigations insuperable difficiilties ; and while, in respect 

 to most of the details which I did succeed in resolving, I 

 agree with him ; I had, before his memoir was published, 

 formed a different judgment as to its zoological position. 



At first sight I was ready to conclude, with Mr. Huxley, that 

 it was an Infusorium of the family JEupIotida ; and, indeed, 

 long before that gentleman's allusion to the Chlamidodon nine- 

 mosyne of Ehi'cnberg, I had shrewd suspicions that our Tenby 

 stranger might be no other than that species. The peculiar 

 outline of the lorica, its delicate longitudinal striation, the 

 "large, oval, bright central gland" (contractile space?), the 

 marginal row of cilia, longer in front, playing beneath the 

 overlapping edge of the lorica, the marine habitat, and espe- 

 cially the brilliant rose-coloured vesicles, are all characters 

 (remarkable in their cumulation) which point to such an 

 identification. It is true there are important diversities be- 

 tween Chlamidodon, as described and figured, and our Dys- 

 teria ; but those who have been accustomed to examine 

 minutely the figures of the eminent Prussian zoologist, and 

 to compare them with the living animals, will not hastily 

 pronounce their identity impossible. 



Presuming Dysteria to be an Infusorium, it must be a 

 species sui generis, with no close affinity with the Euplotidce. 

 An animal whose soft parts are enclosed IjctAveen two deeply 

 compressed valves, and which crawls by the aid of a hinged 

 shelly foot, is widely different from one greatly depressed, 

 covered with a dorsal plate, and Avliose organs of locomotion 

 are short flexible setse, scattered over the soft ventral sur- 

 face. 



But I am by no means sure that it should be placed 

 among the Infusoria at all. Mr. Huxley observes that 

 "the absence in an animal whicli takes solid nutriment, of 

 an alimentary canal with distinct walls, united with the pre- 

 sence of a contractile vesicle, with the power of transverse 



