146 FRESH-WATER RHIZOPODS OF NORTH AMERICA. 



Shell compressed pyriform, longer than broad; in the broader view, 

 with the fundus widely convex, the sides sloping downward and generally 

 slightly inflected towai'd the oral end, which is convex downward; in the 

 narrow view, oblong, with the fundus obtuse, sometimes impressed on each 

 side, gradually sloping, and usually slightly inflected toward the oral end, 

 which is notched Mouth transversely oval, entire. Shell colorless, 

 exceedingly variable in its structural elements, generally composed of oval 

 or circular disks, sometimes nearly exclusively of one or the other, or inter- 

 mingled in various proportions, more or less uniform or variable in size, 

 sometimes mingled with rod-like or narrow rectangular plates, and some- 

 times almost wholly composed of these, rarely composed of thin, irregular, 

 angular plates. Sarcode colorless, resembling in general constitution and 

 arrangement that of Hyalosphenia, etc.; pseudopods digitate, usually from 

 three to half a dozen. 



Size. — In fifty specimens two thirds ranged between 0.1 mm. and 0.14 

 mm. in length. The smallest of the series was 0.064 mm. long, 0.036 mm. 

 broad, 0.02 mm. thick, with the oral end 0.016 mm. broad and 0.008 mm. 

 thick. The largest was 208 mm. long, 0.12 mm. broad, 0.06 mm. thick, 

 with the oral end 0.048 mm. broad and 0.032 mm. thick. An average-sized 

 specimen was 0.128 mm. long, 0.08 mm. broad, 048 mm. thick, with the 

 mouth 0.032 mm broad and 0.024 mm. thick. 



* 



Locality. — Moist sphagnum, of the sphagnous swamps of New Jersey, 

 Pennsylvania, Maine, Florida, Alabama; rarely in moss at the edge of a 

 pond in the Uinta Mountains, Wyoming Territory. 



ftfefoela collaris (pi. XXII ; pi. XXIII, figs. 1-7), a remarkable and 

 beautiful rhizopod, is common and abundant, living in the moist sphag- 

 num of the sphagnous swamps of New Jersey and Pennsylvania. It is a 

 constant associate of Hyalosphenia papilio and H. elegans Sometimes the 

 sphagnum in certain localities actually swarms with the animal, and a 

 drop of water squeezed from the plant contains a multitude of them. At 

 other times and in other localities, apparently under equally favorable 

 circumstances, the sphagnum contains few or none of the animals, though 

 it is rare not to find traces, such as a few dead shells, in the sphagnum of 

 most localities. 



The shell is compressed pyriform, longer than broad, though varying. 



