1(34 FRESH-WATER RHIZOPODS OF NORTH AMERICA. 



Commonly the size of Heleopera picta varies but little, a frequent size 

 being about ^th of an inch in length by ^th of an inch in breadth ; but 

 individuals are met widely differing at different places and seasons. It ranges 

 from 4-th to ith of an inch in length : ~th to Mh of an inch in the greater 



270 lot) " ' ooU lot *-> 



breadth, and Mh to i-,th of an inch in the less breadth. The mouth varies 



* 57U aou 



from ith by JLth of an inch to ith by 7 -f- th of an inch. 



Heleopera picta is frequently found in the encysted condition, in which 

 state the aperture of the shell is closed by a double convex laminated 

 epiphragm of a yellowish or brown color, as seen in figs. 2, 4-7. The 

 encysted sarcode is compressed spherical, occupying the centre of the 

 shell, as seen in the view of the broader surfaces, and in contact with 

 them, as seen in the view of the narrower surfaces. The encysted ball 

 retains unchanged the profusion of chlorophyl corpuscles, which ordinarily 

 obscure from view almost everything else. Commonly a clearer central 

 spot of the ball betrays the presence of a nucleus 



Generally the chlorophyl corpuscles, mingled with colorless granules, 

 form a closely agglomerated mass enveloped with a stratum of colorless 

 granular protoplasm of variable thickness. Most of the chlorophyl cor- 

 puscles appear of nearly uniform size, and in different specimens commonly 

 range from J^th to ^th of an inch in diameter. 



On the 9th of April, 1877, I observed an individual of H. picta, ob- 

 tained from sphagnum preserved all winter in a glass case, with the 

 appearance represented in fig. 2. The interior encysted ball was about 

 j^th of an inch in breadth, and contained the usual agglomeration of chlo- 

 rophyl corpuscles, of comparatively uniform size, including a nucleus. 

 The agglomeration was capped on one side by a large accumulation of fine 

 molecules, which by reflected light appeared milk-white. 



Individuals of H. picta are found, as represented in fig. 8, in which the 

 mouth of the shell is closed by an epiphragm ; but the usual sarcode mass 

 is replaced by a multitude of more or less scattered chlorophyl corpuscles, 

 like those which ordinarily occur within the sarcode. These are probably 

 spoi-es or germs derived from the breaking-up of the latter. 



Sometimes, also, individuals are seen in which the shell, with the 

 aperture open or closed, contains a multitude of yellowish bodies, as seen 

 in fig. 10, which resemble the chlorophyl corpuscles deprived of their 

 bright green hue. 



