PELOMYXA VILLOSA. 8] 
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 » 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. 
Genus 5. LITHAMCBA Ray Lankester, 1879. 
Lithameba Ray Lanxsster in Q. J. Micr. Sci. XIX, us. 
(1879), p. 484. 
Body amoebiform, 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 dAinwba, this 
genus has a characteristic nucleus, and the peculiar 
concretions (on which the name is founded) further 
distinguish it. 
1. Lithameba discus Ray Lankester. 
(Plate V, fig. 5.) 
Dithameba discus Ray Lanxesrer in Q. J. Micr. Sci. XTX, 
n.s. (1879), p. 484, t. xxiii; and in Encycl. Brit. ed. 9, 
XIX (1885), p. 843, f. v. 
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