PELOMYXA VILLOSA. 81 



are small and inconspicuous, usually posterior; the 

 nuclei as in the preceding species. 



Dimensions variable ; usually much smaller than 

 P. palustris ; active individuals 250 ^ in longest 

 diameter, and 100-130 p, in width anteriorly. 



In the ooze of shaded ponds, with the preceding 

 species ; also in ditches and bogs. 



The caudal bulb of P. villosa, though capable of 

 modification, and even of temporary extinction in the 

 active life of the animal, is nevertheless sufficiently 

 distinctive, as, however obliterated in form, it always 

 returns to the normal condition. In some attitudes, 

 as when the body expands laterally, the villi become 

 spread out along the margin, forming a kind of frill. 

 This, however, is only a temporary phase. 



Grenus 5. LITHAMCEBA Ray Lankester, 1879. 



Litltamwba RAY LANKESTER in Q. J. Micr. Sci. XIX, n.s. 

 (1879), p. 484. 



Body amcebiform, discoid, with a rounded or sub- 

 elliptic outline, distinguished by the presence within 

 the semitransparent endoplasm of numerous concre- 

 tionary elements, varying in size, and reniform ; 

 pseudopodia lobular, hernia-like, never digitate ; the 

 nucleus large and conspicuous, punctated. 



Whilst having a general resemblance to Amoeba, this 

 genus lias a characteristic nucleus, and the peculiar 

 concretions (on which the name is founded) further 

 distinguish it. 



1. Lithamoeba discus Ray Lankester. 

 (Plate V, fig. 5.) 



Lithamceba discus RAY LANKESTER in Q. J. Micr. Sci. XIX, 

 n.s. (1879), p. 484, t. xxiii ; and in Encycl. Brit. ed. 9, 

 XIX (1885), p. 843, f. v. 



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