PELOMYXA PALUSTRIS. 79 



large solid or rigid body," when the contour becomes 

 temporarily quite ragged, and whip-like pseudopodia 

 of exceeding fineness are shot out with great sudden- 

 ness and velocity, extending to a considerable length. 

 " Pseudopodia of this kind," the author remarks, " are 

 exceedingly attenuated and acute, and are, for a great 

 part of their length from the tip inwards, perfectly 

 hyaline, appearing to be actual prolongations of the 

 hyaline border ; they often, but by no means always, 

 radiate outwards, and very frequently anastomose, the 

 connecting bridge between two pseudopodia being 

 sometimes hyaline, but more often consisting of fine 

 strands of granular protoplasm."* 



As bearing on the subject of classification, we are 

 unable as yet to see that the production of these fine 

 and occasionally anastomosing pseudopodia are of any 

 special significance. They are evidently adventitious, 

 depending upon conditions peculiar to the individual, 

 and not characteristic of the species in the absence of 

 such conditions. It does not appear that they perform 

 any natural function. They are projected " with great 

 suddenness and velocity," when some hard substance 

 'is being got rid of, and so soon as the producing cause 

 is withdrawn, they are re-absorbed. In other words, 

 their production is the result of a sudden rupture of 

 the ectosarc, occasioned by the accidental circumstance 

 of a foreign body having to be ejected at that spot. 

 This removes them from the category of true pseudo- 

 podia, and marks an essential difference between them 

 and the finely-attenuated and anastomosing pseudo- 

 podia which distinguish the Reticulosa. 



2. Pelomyxa villosa Leidy. 

 (Plate VII, figs. 4-6.) 



Amoeba villosa (Wallich) SLACK in Lit ell. Obs. Ill (1863), 



p. 430, ff. p. 433. 

 Amfieba sabulosa LEIDY in Proc. Acad. Nat. Sci. Phil. 1874, 



p. 87. 



* Loc. cit., p. 390. 



