390 GENERAL HISTORY OF THE INFUSORIA. 



" The appendage referred to is attached to the surface of the body, rather 

 towards the convex side, at the bottom of the ventral groove, and is distant 

 about one-fifth of the whole length from the posterior extremity. It is 

 -g^th to Y^jL_th of an inch in length, and is not altogether unlike a boot 

 with a veiy pointed toe in shape ; and the toe appears to be viscid at its 

 extremity, so as readily to adhere to any foreign object. The appendage 

 then forms a pivot on which the whole body turns about ; and this appears to 

 be the habitual and favoimte position of the Dysteria. 



" Internally, the appendage contains a canal, mder above than below, and 

 apparently bhnd at each extremity. 



" No ' nucleus ' could be found, though carefully sought for with the aid 

 of acetic acid. 



" The occurrence of transverse fission was noticed veiy distinctly in one 

 case ; but it is remarkable that, notwithstanding the great number of speci- 

 mens which were observed, no other instance of this mode of multiplication 

 came under the notice of Mr. Dyster or myself. It would appear that the 

 * apparatus ' disappears, and is reproduced during fission ; for, in the single 

 case observed, mere rudiments of it were to be seen in each half of the 

 strongly-constricted mass. 



'^Dysteria has not hitherto been observed to become encysted, although 

 this condition has been carefully sought for. 



" The creatm-e was foimd in swarms among the Algae, coating the shells 

 of a Patella and a Littorina which had long inhabited a marine vivarium. 



" There can " (p. 82) " be little doubt as to the true systematic position 

 of Dysteria. The absence, in an animal which takes solid nutriment, of an 

 alimentary canal Tvdth distinct walls, united with the presence of a contrac- 

 tile vesicle, with the power of transverse fission, and with cilia as locomotive 

 organs, is a combination of charactei's found only in the Infusoria. In this 

 class, again, the existence of a sort of shell or lorica, constituted by the 

 structui^eless outer layer of the body ; the presence of a submarginal ciliated 

 groove around a large part of the margins of the body ; and the inequality 

 of the two lateral halves, leave no alternative save that of arranging Dysteria 

 near or in the Euplota of Ehrenberg. 



" Indeed, there is one species figured by Ehrenberg {Infusionstliierchen, 

 p. 480, pi. 42. fig. 14), Euplotes macrostylus, found at Wismar, on the Baltic, 

 which, in general aspect, and in the possession of a foot-like appendage, 

 so closely resembles the present form, that, were it not for the absence of 

 any allusion to the amethystine globule, or to the ' apparatus,' I should be 

 strongly inclined to think it identical with Dysteria. That an internal 

 armature is not inconsistent with the general plan of the Euplota, is shown 

 by Chlamidodon, whose apparatus of styles would probably repay re-exami- 

 nation. 



" Notwithstanding certain analogies which might be shown to exist be- 

 tween the manducatory apparatus of some Rotifera (see, e. g., that of Furcu- 

 laria mariyia, figured by Mr. Gosse, in his excellent memoir, Phil. Trans. 

 1846) and the * apparatus ' of Dysteria, 1 see no grounds for regarding the 

 latter as in any way an annectant form between these groups." 



Mr. Gosse dissents from this conclusion of Prof. Huxley relative to its 

 connexion with Euplota, and considers it a member of the family Monocer- 

 cadece among the Rotifera. 



" Presuming," he says (J. M. S. 1857, p. 138), " Dysteria to be an In- 

 fusorium, it must be a species sui generis, with no close affinity with the 

 Euplotidce. An animal whose soft parts are enclosed between two deeply- 

 cowpressed valves, and which crawls by the aid of a hinged shelly foot, is 



