LITHAM@BA DISCUS. 83 
The nucleus is large, peculiar in shape (“‘block-like’’), 
distinctly punctated or tesselated, and has a definite 
capsule. In the structure of this organ, and the delicate 
cuticle of its protoplasm, Lithameaba is considered by 
its author as “unlike any other form, whilst the com- 
bination of characters which it presents entitles it to a 
very distinct position among the amceboid Gymno- 
myxa.” 
The organism is apparently very rare. We have 
not met with it. The foregoing description is taken 
from Prof. Lankester’s monograph. 
Genus 6. OURAM@GBA Leidy, 1879. 
Ameeba (pars) ARCHER in Q. J. Micr. Sci. VI, ns. (1866), 
190 
p. 190. 
Ourameba Leipy Freshw. Rhiz. N. Amer. (1879), p. 66. 
Body amceboid, with a granular endoplasm, a single 
contractile vesicle, and discoid nucleus. Pseudopodia 
digitate, arismg from any part of the body-surface, 
usually anterior; the posterior extremity habitually 
furnished with one or more tufts of rigid, linear, non- 
contractile protoplasmic filaments, branching radially 
from points in the vicinity of the contractile vesicle. 
The posterior filaments, which are the peculiarity of 
this genus, alone distinguish it from Ame«eba. These 
filaments are sometimes cast off, and by some authors 
have been held to be of no physiological significance. 
1. Ourameeba vorax Leidy. 
(Plate V, fig. 6.) 
Aimuba villosa (Wallich) ArcHeR in Q. J. Micr. Sci. VI, 
ns. (1866), p. 190; op. cit, X, n.s. (1870), p. 305; in 
Journ. Dublin Micr. Club, I, 2 (1867), p. 56; and op. cit. 
II, 1 (1872), p. 15. 
Anueba villosa? Arcuer in Q. J. Micr. Sei. XIV, ns. (1874), 
p. 212, and in Journ. Dublin Micr. Club, II, 3 (1875), 
p. 314. 
