800 ORDER HYPOTRICHA. 



quoted in the foregoing diagnosis. Among the numerous synonyms with which this 

 abundantly distributed species has been connected by the earlier writers, the follow- 

 ing, as given in Stein's monograph of the Hypotricha, may be more especially 

 mentioned : Trichoda charon and cimex of Miiller ; Euplotes charon and appendiculatus 

 of Ehrenberg ; and Plxsconia charon, affinis, subrotunda, radiosa, and longiremis of 

 Dujardin. 



GENUS VI. STYLOPLOTES, Stein. 



Animalcules free-swimming, encuirassed, elliptical, turgid, the carapace 

 rounded and thickened at the lateral margins, with a projecting antero- 

 dorsal lip ; the hinder extremity obliquely truncate ; a band-shaped median 

 channel or excavation extending from one end to the other of the ventral 

 surface, in which are situated the arcuate peristome-field and also the stout 

 frontal, ventral, and anal styles or uncini. In addition to these last-named 

 elements, a supplementary postero-marginal fascicle of caudal styles is 

 usually developed. 



Styloplotes appendiculatus, Ehr. sp. PL. XLIV. FIGS. 30 AND 31. 



Body elliptical, the anterior end ovoid, somewhat pointed, the posterior 

 extremity obliquely truncate, curved to the right; five frontal and four 

 ventral styles, two of the latter situated in the centre of the median groove, 

 and two near the left lateral border ; anal styles very long, five in number, 

 variously curved, closely approximated, and forming a single transverse row, 

 which projects considerably beyond the posterior margin ; a supplemen- 

 tary postero-terminal or caudal series, composed of three recurved uncini, 

 developed upon the posterior border. Length of body 1-380" to 1-260". 



HAB. Salt water. 



Stein identifies this species with the Stylonychia appendiculata of Ehrenberg, 

 the Ploesconia scutum (in pars) and Diophrys marina of Dujardin, and with the 

 Euplotes excavates and Schizopus norvegicus of Claparede and Lachmann. 



The author has recently obtained it in abundance in the neighbourhood of 

 St. Heliers, Jersey, and had then under examination an apparent embryonic form. 

 The complete life-history was not fully traced, but it was observed that in an early 

 stage of development it differs remarkably from the adult animalcules, possessing 

 no frontal, ventral, or anal styles, but simply an anterior or adoral fringe of cilia. 

 Under these conditions its movements are almost exclusively natatory, its translation 

 through the water being very swift, and its general aspect somewhat approaching 

 that of a Strombidium. 



The type referred to the family Euplotina by Ehrenberg, under the title of 

 Himantophorus charon, is regarded by Stein as not improbably identical with 

 Onychodromus grandis. The Discocephalus rotatorius of the same author is 

 apparently an imperfectly observed representative of the genus Aspidisca. 



