EDMONDSON — PROTOZOA OF IOWA. II 



In size this species is almost as large as Amceba proteiis, differ- 

 ing from the last named species, however, in possessing rather well 

 defined anterior and posterior extremities. The species is usually 

 remarkably active, progressing with rapidity in a definite direc- 

 tion by a forward rolling motion, the broad end preceding. 



Pseudopodia, when they make their appearance, which is sel- 

 dom, are broad and lobe-like. The villous appearance of the 

 knob-like posterior extremity, which characterizes the vSpecies, is 

 probably due to a rapid shrinking awaj^ of the protoplasm of this 

 region as the animal rolls forward in its customary movement 



In appearance Aimvba villosa is light yellowish, the endoplasm 

 usually being crowded with food materials consisting of diatoms, 

 algae, etc. A nucleus and a contractile vesicle are present, the 

 former, however, often being obscured and not observed without 

 the use of reagents. 



This species has been obtained in great numbers from the sed- 

 iment at the bottom of a long standing infusion of pond water. 



I have not observed the species in this state except in Johnson 

 county, although no doubt its distribution is general. 



I^ength, reported by Wallich, i-5oth of an inch. Specimens 

 observed in this state, about 200 microns in length. 



Amceba verrucosa Ehr. 



Body usually rounded, very transparent. Pseudopodia short, 

 broad, blunt. Ectoplasm extensive in comparison with the more 

 granular endoplasm. Upper surface usually wrinkled, giving the 

 appearance of longitudinal lines. 



Length, 50 microns. (Fig. 4, PI. I.) 



Amoeba verriicosa, in the adult stage, is a very sluggish form, 

 its chief movement being a slow, rolling motion, while short, lobe- 

 like pseudopodia may be slowly extended. Immature individuals 

 are much more active, moving with a broad extremity in advance. 



The longitudinal wrinkles, of which there are usually four ex- 

 tending from the posterior nearly to the anterior extremity, seem 

 to be but temporary folds of the ectoplasm. They are not at all 

 times constant in number in the same individual and, in some, not 

 appearing at all. 



Amceba verrucosa is apparently neither abundant nor widely dis- 

 tributed in this state. The few individuals observed have been 

 found in diatomaceous ooze from pond water. 



