GENUS CHLOROMONAS. 401 



each instance being so complete that the side affected by it presents a temporary 

 aspect of complete collapse. This locomotive phenomenon, taken together with the 

 very distinctive contour and structure of the organism as a whole, differs so essenti- 

 ally from Leptodiscus medusoides in its normal state that it is almost impossible to 

 repress the suspicion that this more minute organism will eventually prove to belong 

 to an independent and perfectly distinct pelagic type. 



Section B.EUSTOMATA-DIMASTIGA. 

 Fam. V. CHRYSOMONADID.S3, S. K. 



Animalcules bi-flagellate, rarely monoflagellate, social or solitary, free- 

 swimming or adherent, naked, loricate, or immersed within a common 

 mucilaginous matrix or zoocytium ; endoplasm always containing two 

 lateral, occasionally green, but more usually olive-brown or yellow, differ- 

 entiated pigment-bands ; one or more supplementary eye-like pigment- 

 spots frequently present. 



The considerable series of genetic types assembled in this newly proposed family 

 group are at once recognized by the presence of the characteristic lateral pigment- 

 bands, these elements being here held to be of such primary import as to over- 

 ride the fact that in the first three genera described a single flagellum only has as 

 yet been detected. The colour-bands in question, in addition to their distinctive 

 tint, are apparently of firmer consistence than the surrounding transparent proto- 

 plasm, and bear a very considerable resemblance to the endochrome or colouring 

 matter of the Diatomaceae. The development of these pigment-bands, though 

 constant among zooids of the same species, varies considerably among different 

 generic and specific forms, being symmetrical or unsymmetrical, and produced 

 either in whole or in part only down the lateral borders of the animalcule's body. 

 While until recently the affinities of these animalcules were accepted as closely 

 approximate to that of Volvox, Protococcus, and other undoubted Protophytes, the 

 most recent researches of Stein, in combination with the independent investigations 

 of the present author, have substantiated in many instances as, for example, the 

 genera Dinobryon, Uroglena, and Chrysomonas their undoubted animal organiza- 

 tion. So far as at present known, all the members of this family are inhabitants of 

 fresh water. 



GENUS I. CHLOROMONAS, S. K. 

 (Greek, chloros, green ; monas.) 



Animalcules more or less ovate, solitary, free-swimming, persistent in 

 shape, flagellum single, terminal ; endoplasm enclosing two differentiated 

 lateral pigment-bands, and usually an anterior eye-like pigment-spot. 



This new genus is instituted for the distinction of the form identified by Stein 

 with the Cryptoglena pigra of Ehrenberg, but which, as presently explained, differs 

 essentially from the typical Cryptoglentz in the possession of the characteristic colour- 

 bands and of a single flagellate appendage. 



Chloromonas pigra, Ehr. sp. PL. XXII. FIGS, i AND 2. 



Body ovate or conical, somewhat compressed, pointed posteriorly, the 

 cuticular surface indurated and presenting sharpened or keel-like lateral 

 borders ; pigment-bands bright green, extending evenly on each side 

 throughout the length of the body ; eye-like pigment-spot immersed within 



2 D 



