GENUS PELOMYXA— PELOMYXA VILLOSA. 75 



Pelomyxa villoma ordinarily ranges in its more matured forms from 

 0.166 to 0.33 mm, though rarely I have seen individuals reaching 1.25 

 mm. in diameter, or 1.75 mm. in length by 1 mm. in breadth, so that the 

 largest specimens are intermediate in size to the largest of those of Amoeba 

 villosa and Pelomyxa palustris. 



Pelomyxa villosa viewed by reflected light, as seen in figs. 1, 11, 13, 

 14, usually appears cream-colored, yellowish white, or brownish white, 

 often more or less spotted with various colors, green, yellow, and brown, 

 due to particles of the food contents shining through. It is mostly opaque 

 or nearly so, and viewed by transmitted light, as seen in figs. 2-4, 6, 10, 12, 

 17, appears dark brown or black, with a thin hyaline border, which widens 

 to a more or less prominent meniscus-like thickening in advance of any 

 pseudopodal projection. Small or young individuals are proportionately 

 more and more translucent, as seen in figs. 5, 7-9, 15, 16. 



When at rest the animal is somewhat depressed globular or oval, and 

 ordinarily when starting to move it assumes an ovoid, oblong, or clavate 

 shape. In progression it is commonly sausage-like in form, straight, more 

 or less curved or sigmoid, and habitually moves with the thicker end in 

 advance. The posterior — usually narrower — end mostly is more or less 

 finely villous ; and this portion frequently projects as a depressed ball or 

 disk, or as a process of variable form and extent. 



The animal may move along in a slow steady roll or flow, with little 

 change of shape, preceded at the fore end by a continued or more or less 

 interrupted advance of a meniscus-like extension of clear ectosarc, pursued 

 closely by an incessant influx of the endosarc. Mostly the progressive 

 movement occurs through the alternate projection on each side of the head 

 of a hemispherical portion of the ectosarc followed by a rather abrupt and 

 quick rush of the endosarc into the pseudopodal projections. 



Dr. Wallich's remarks concerning the movements of Amoeba villosa 

 apply equally well to those of the form under consideration. He says that 

 "the rush of granules of the sarcode does not follow upon a previous con- 

 tractile effort exercised at the posterior portion. As the animal progresses, 

 occasionally altering its course, there are periods during which perfect 

 quiescence is maintained by the granules; and the rush or flow of these 

 seems to take place, as it were, to fill up the vacuum engendered by the 

 sudden projection of a portion of the ectosarc." * 



"Annals and Magazine of Natural History, 1663, xi, 369. 



