AMCEBA VEBfiUCOSA. 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 200 /*. (Maximum 300-350 /i, 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 Amoeba 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 in this animal. 



A. verrucosa is an omnivorous feeder. Besides 

 desmids and other alga3, 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. stritttn 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 (PI. 

 V, figs. 1 a, b, c), 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 



