54G SYSTEMATIC HISTORY OF THE INFrSORIA. 



thicker trailing one acting as a retractor. This genus, by possessing the two 

 filaments of different characters and office, approaches the Heteromita and 

 Anisonema, from which, however, it is distinguished by its contractile, ob- 

 liquely striated integimient. 



Heteronema marina (xxvi. 11). — I narrower in front, obliquely and closely 

 Body oblong, irregidarly dilated behind, | striated. Length 1-434". In sea-water. 



Genus POLYSELMIS (Duj.) (XXVI. 7).— Animal oblong, of vaiiable form, 

 swimming by means of several flagellifonn filaments which aiise from its 

 anterior extremity. The single Infusorium I have found possessing these 

 characters resembled an oblong Euglena rounded at each end, with an anterior 

 longer moveable filament, surroimded by three or four very fine shorter ones, 



PoLYSELMis t7nV7/s (xx\T[. 7). — Elon- with a red eye-speck. 1-650". Found in 

 gated, rounded at each end ; more or less a glass of marsh-water containing Lemna, 

 dilated and folded in the middle ; green, which had been kept several months. 



Genus EUTPEPTIA (Perty) (XYIII. 53-55).— Like CUorogonium, Zygo- 

 sehnis, and Dinema, has two filaments. It has besides the form of an Astasia, 

 but its figure is constantly varying as it swims, and it has a red stigma. 



This and the following genus constructed by Perty are very imperfectly 

 characterized, and in oiu- opinion have slight claim to generic independence. 



EuTREPTiA viridis (xviii. 53-65 ; xix. a crawling movement, and not the power 

 18-19). — Green, with hyaline corpuscles, of swimming. Length, when extended, 

 but sometimes quite colourless. A va- 1-240". Among Lemnae. A variety, E. 

 rietj" thick and rounded posterior, with iinijilis, has only a single flabellimi and a 

 the outline oi Amhiyophis, only presented faintly marked stigma. 



Genus DINEMA (Perty) (XIX. 17). — Filaments two; one projected in 

 advance, the other trailed behind. Body small, saccular, very contractile, and 

 destitute of chlorophyll. 



Dinema griseolnm (xix. 17). — Body 

 filled with grey molecules. Movements 

 sluggish, and pai-ticidarly so the rotation 

 on its long axis. Filaments about equal in 



dimensions. 1-250". Bern. In ponds, &c. 

 D. jmsilhmi. — Colourless, with few in- 

 ternal granules. Very contractile, and 

 changeable in figure. 



FAMILY DIXOBRYINA. 



(XXII. 42, 48, 49.) 



The animalcules of this family are distinctly, or to all appearance, poly- 

 gastric, and furnished with only one aperture to the body ; hence, Uke 

 polj^es, they can have no true alimentary canal. They are possessed of an 

 external case or sheath, and have the power at will of changing their form, 

 but are without appendages, except one species of Dinohryon, which has a 

 simple filiform proboscis and a dehcate red spot at the anterior portion of the 

 body. The nutritive apparatus is obscure and undefined. The lorica is of the 

 form of a little pitcher (urceolus), to the bottom of which the very contractile 

 Euglena-like creature is attached. Two genera only are known. 



Genus EPIPYXIS (XXII. 42).— The characteristics of this genus are 

 mostly of the negative kind ; it wants the eye, and is attached. The most 

 evident animal character possessed by the species is the funnel-shaped orifice 

 at its anterior extremity. The soft or pulpy body is lodged within a deHcate 

 membranous (not sihcious) lorica, usually affixed by a pedicle or foot. 



Stein presumes Epipyxis to be merely a younger condition of Dinohryon, 

 with which it occurs frequently in company. Besides this, the peculiar cell- 

 like nucleus occurs alike in Epipyccis and in Din. Seriularia. 



