8 FRESH- WATER RHIZOPODS OF NORTH AMERICA. 



with the Foraminifera, Protoplasta, and Monera, as Rhizopoda, but propose 

 for this class to substitute the name of Sarcodina. 



In my studies of the Protozoa, or animals of the lowest subkingdom, 

 I have habitually viewed as Rhizopods the five ordinal groups indicated 

 in the above classification. This accords with the views of Prof. F. E. 

 Schulze, an able investigator of the class. In a recent number of the 

 Archiv fur Mikroscopische Anatomie for 1877, p. 21, he remarks, that his 

 researches led him to consider as pertaining to the Rhizopods, as an 

 essentially harmonious whole, all those low forms which, during the greater 

 part of their life, and especially during the period of their highest perfec- 

 tion, hold intercourse with the exterior world, move about, and obtain food, 

 by means of extensile processes of the viscid body-substance, which are 

 again capable of flowing back completely into the latter. 



The first two orders of the Rhizopods — the Protoplasta and the Heliozoa — 

 are those which are commonly designated as the 'Fresh-water Rhizopods'; 

 the Radiolaria and the Foraminifera, with part of the Monera, are marine. 



Fresh-water Rhizopods are to be found almost everywhere in positions 

 kept continuously damp or wet, and not too much shaded. They are 

 especially frequent and abundant in comparatively cpiiet waters; clear, and 

 neither too cold, nor too much heated by the sun, such as lakes, ponds, 

 ditches, and pools. They are also frequent in wet bogs and savannas, 

 among mosses, in springy places, on dripping rocks, the vicinity of water- 

 falls, springs, and fountains, and in marshes, wherever the ground is suffi- 

 ciently damp or moist to promote the growth of alga? They are also to 

 be found in damp shaded places, among alga?, liverworts aud mosses, about 

 the roots of sedges, rushes and grasses, or those of shrubs and trees grow- 

 ing in or at the borders of bogs and ponds or along ditches and sluggish 

 watercourses. They are likewise to be found with algae in damp shaded 

 positions in the depressions and fissures of rocks, in the mouths of caves, 

 among decaying logs, among mosses and lichens, on the bark of growing 

 trees, and even in the crevices of walls and pavements about old dwellings 

 and in cities. 



The favorite habitation of many kinds of Rhizopods is the light super- 

 ficial ooze at the bottom of still waters, where they live in association witli 

 diatoms, desmids, and other minute alga?, which form the chief food of 

 most of these little creatures. They never penetrate into the deeper and 



