92 FEESH- WATER RHIZOPODS OF NORTH AMERICA. 



surrounded by a clear halo. Pointed conical pseudopods of clear ectosarc 

 projected everywhere from the head and body, while the tail was minutely 

 and profusely papillose. 



When next examined, the animal appeared as in fig. 6, oval in outline, 

 with the anterior half covered with pseudopods, and the posterior half with 

 numerous short blunt papillae. The nucleus was concealed from view. 



Later the body was elongated, with the posterior part most expanded, 

 as in fig. 7. The nucleus was nearly central and quite distinct. In the 

 first and last views, several small contractile vesicles were observed at the 

 posterior extremity of the animal. 



Among the articles of food there was a long colorless thread, appar- 

 ently a cotton or ligneous fibre, coiled among the other constituents of the 

 endosarc. A bright green desmid, as seen in figs. 5, 6, finally assumed a 

 brown hue, as seen in fig. 7. 



Fig. 8 represents an individual of the same kind as the preceding, in 

 the act of floating or swimming. The body of globular form, and with 

 numerous pointed pseudopods radiating in all directions, gave it the general 

 appearance of a Heliozoan, except in the character of the rays. The usual 

 posterior papillae did not appear in this condition, but subsequently were 

 seen, when the animal assumed the elongated creeping position. The size 

 of the central body was ranch, reduced in its proportions, from the multi- 

 tude of pseudopodal rays, and measured 0.065 mm. in diameter. 



The endosarc of the amoeboid under consideration is usually pale gran- 

 ular, and apparently mingled with brownish matter, which I have suspected 

 to be derived from the brown flocculent material usually so abundant in 

 the locality in which the creature is found. It also contains variable pro- 

 portions of fine oil-like molecules, water-vacuoles, brownish and colorless 

 granular food-balls, diatoms, and other food materials, but rarely a particle 

 of quartz-sand. Mostly the fine oil-like molecules are very few or are 

 altogether absent, and frequently also water-vacuoles appeared not to be 

 present except in the nature of contractile vesicles. Of these there are 

 apparent a variable number situated within the villous extremity of the body, 

 often small and comparatively numerous, at other times few and larger. 



Commonly a nucleus may be detected in the movements of the animal, 

 as seen in figs. 5 and 7. It is of large size, pale granular, and surrounded 

 by a clear ring. In fig. 10, an individual is represented, in which the 



