54 BRITISH FEESHWATEE EHIZOPODA. 



The animal makes a slow but continuous advance, 

 and during its movements the semi-fluid endoplasm 

 flows longitudinally, in distinct streams, modifying, 

 by pressure, the form of the contractile vacuole, 

 which at one moment may be circular and the next 

 elongated or irregularly outlined. The endoplasm is 

 finely granular, colourless, or tinged with green from 

 the presence of minute chlorophyl particles, and it 

 contains also a limited number of larger granules or 

 crystalline bodies of irregular shape. 



Dimensions: Length 25-45 ,; greatest breadth an- 

 teriorly 20-35 p. 



In ponds amongst submerged vegetation, usually 

 common. 



The contractile vesicle, in this species, is curiously 

 modified by the flow of the endoplasm. Whilst 

 changing in position but slightly, its form exhibits 

 constant variation. It will reappear, after discharge, 

 sometimes as two separate vesicles of small size ; these 

 gradually enlarge, and ultimately unite ; and the organ 

 not infrequently presents an oval or distorted outline. 



Amoeba striata has been, by some, regarded as a young 

 state of A. verrucosa Ehrenb. Leidy (' Freshw. Rhiz. 

 N. Amer.') so describes and figures it. Apart from 

 the fact that it is a much smaller organism, and 

 possessed of characters of its own, which are constant, 

 it is rarely found in association with A. verrucosa in 

 the adult state. 



6. Amoeba guttula Dujardin. 

 (Plate V, fig. 4.) 



Amiba guttula DUJAEDIN Infus. (1841), p. 235; CEEVIER in 



Nat. Canad. VII (1875), p. 276. 

 Amoeba guttula PEETY Kenntn. kleinsi. Lebensf. (1852), 



p. 188, t. viii. f. 13; PEITCHAED Hist. Infus. new ed. 



(1852), p. 203, and ed. 4 (1861), p. 549, t. xxii, f. 6; 



AUERBACH in Zeits. f. wiss. Zool. (1856), p. 414, t. xxii, 



ff. 17, 18 ; WILLIAMSON in Pop. Sci. Rev. V (1886), p. 197, 



