246 Mr. H. J. Carter on Ploesconia and Kerona. 



form of the legs, while their office, being essentially locomotive, 

 demands the more appropriate appellation of "legs/' In de- 

 scribing these animalcules, too, it will be necessary, if we are 

 ever to make any advance in our knowledge of their species, 

 to determine the number of the legs, as well as their position 

 and form, together with that of the body ; for there are some 

 species which approach others so nearly in the latter, that the 

 form or number of the legs alone presents the chief distinguish- 

 ing character. 



Multiplication by transverse division is common in P. trun- 

 cata ; but I have not yet seen longitudinal division in this species. 



Ploesconia Charon, Duj. Euplotes Charon, Ehr. 

 PI. VI. figs. 12-15. 



Oval, slightly truncated anteriorly. Dorsal surface convex, 

 divided into 5-6 longitudinal ridges, which are granulated on 

 the margins, and radiate meridionally from a caudal point. 

 Ventral surface plane, irregular, furnished with a gill and 

 fifteen large styliform legs, of which five are posterior and do 

 not appear to terminate in lashes of hairs, and the rest anterior. 

 Small legs four in number, situated posteriorly and laterally, 

 fixed to the ventral surface submarginally, two on one side, 

 and two on the other of the median line, all styliform. Anal 

 orifice and contracting vesicle situated together on the right 

 side, marginally, and a little posteriorly. In other respects 

 this species is constructed so like P. truncata, that, with a re- 

 ference to the illustrations, no further description is necessary. 

 Nucleus not seen. Length varies from 1 -700th, which is the 

 smallest size I have seen, to 1 -300th of an inch. 



Hah. Salt and fresh water, especially the former in the main 

 drain of the island of Bombay, feeding on small animalcules, 

 Diatomacese and Algse. 



Loc. Island of Bombay and Europe. 



Obs. I have not been able to see the granulations on the 

 ridges, but their existence may be inferred from their impressions 

 being left on the empty capsules of this species after its elimina- 

 tion, as will be more particularly noticed hereafter (fig. 19). In 

 some instances that part of the border between the posterior mar- 

 gin and the gill is so much expanded, that at first sight it seems 

 to indicate a diff"erent species ; but I think this will be found to 

 be owing chiefly to a more fully- developed or robust form of the 

 animalcule, probably under the influence of good food. Some in- 

 dividuals are frequently not more than one-third of the size of the 

 largest of the kind ; and although diminution to a certain extent 

 is often owing to want of nourishment, yet, when they are so 



