AMGBA VERRUCOSA. 61 
perceptible. Endoplasm granular, sub- -transparent, 
containing a spherical nucleus, and (in the posterior 
region) a contractile vacuole, which is usually con- 
spicuous, together with a variety of food-remains, 
animal or vegetable, or both. Habit very sluggish. 
Dimensions variable. Average length, during rapid 
march, about 2004. (Maximum 300-350 «, Greeff.) 
In the ooze of ponds, amongst submerged vegeta- 
tion, in tufts of moss growing on moist rocks, and in 
marshy places; widely distributed, but less common 
than A. proteus. 
The characters and habit of Ameba verrucosa separate 
it distinctly from every other member of the genus. 
The crinkled or striated ectoplasm is indicative of an 
unusual degree of surface-hardening, but cannot be 
regarded as evidence of a permanent envelope. The 
lines are often numerous and extremely delicate, 
extending longitudinally from the vicinity of the con- 
tractile vesicle forward to the anterior ectoplasm. 
They are most distinct at or near the margins where 
the protoplasm is least dense. The short, blunt, and 
generally very persistent wart-like protuberances on 
the surface of the body are a further distinctive 
feature. Pseudopodal movement is slow 1 in this animal. 
A. verrucosa 18 an omnivorous feeder. Besides 
desmids and other alge, individuals are sometimes 
found which contain the half-digested remains of 
infusorians and rotifers. (Pl. IV, fig. 1.) 
Some observers (e.g. Leidy in ‘Freshw. Rhiz. N. 
Amer.’) have regarded what has since been described 
as A. striata Penard, as a young state of the species 
under notice—probably on insufficient grounds. The 
young of A. verrucosa, which we have sometimes met 
with, is normally a sub-spherical pellucid body (Pl. 
V, figs. la, 6, ¢), containing some granular, almost 
colourless endoplasm, and furnished with a nucleus 
and contractile vesicle. There is the wrinkled envelope 
of hyaline ectoplasm, extremely delicate, but clearly 
