54 FRESH WATER RHIZOPODS OF NORTH AMERICA. 



more or less wrinkled condition of the surface; pseudopods short, broad, 

 blunt lobate extensions of the ectosarc; outlines of the body, wrinkles of 

 the surface, and pseudopodal extensions more or less sharply defined, and 

 often appearing with double lines. Endosarc pale gi-anular, and mostly, 

 excepting food materials, with few or no coarse granules. Ectosarc 

 copious, very hyaline, and broadly extended. Contractile vesicle large and 

 conspicuous. Nucleus mostly distinct. Size ordinarily ranging from 0.08 

 by 0.072 mm. to 0.18 by 0. 1 6 mm., or from about ith to -Jth of a millimetre. 



Animal in the younger stages active and incessantly in motion; body 

 oval or pyriform, usually moving with the broader pole in advance; surface 

 comparatively smooth, but marked with four longitudinal lines or delicate 

 folds, sometimes with a greater or less number or none. Fore part of the 

 body appearing as a broad, clear pseudopodal expansion thinning away 

 laterally and posteriorly. Contractile vesicle posterior; nucleus in advance 

 of the latter. Size ranging from 0.04 by 0.02 mm to 0.12 by 0.09 mm. 



Locality. — Very common, and found almost everywhere with moisture 

 and algae. Pennsylvania, New Jersey, Ehode Island, Connecticut, Maine, 

 Nova Scotia^ Colorado, Wyoming, and Utah. 



Ehrenberg described, in the 'Infusionsthierchen,' a species of Amoeba 

 with the above name as follows: "In the extended condition small, not 

 exceeding ith of a line, hyaline, sluggish, with variable processes which 

 are very small, obtuse, and wart-like." He remarks that he never saw the 

 processes reach even half the extent of the body. The animal remained a 

 long time motionless, but appeared voracious, as it invariably contained 

 Oseillarise or Naviculse mostly half digested. It also contained a nuclear 

 body and a contractile vesicle. The short, wart-like processes were always 

 blunt. 



Dujardin refers a small Amoeba to the same species, and describes it 

 as globular or ovoid, with short, cylindrical, obtuse, divergent expansions 

 frequently appearing like warts, with very slow motion, aad measuring 

 from 0.014 to 055 mm 



Perty indicates Amoeba verrucosa, and describes a small Amoeba with 

 the name of Amceba natans, which is probably the same, for he says this 

 is like the former, but smaller, being only the g'^th of a line. 



An Amoeba agreeing with the description oi Amoeba verrucosa of Ehren- 

 berg I have frequently obtained from various localities. I have found 



