252 FRESHWATER RHIZOPODS OF NORTH AMERICA. 



very long. In solitary individuals they emanate from all parts of the sur- 

 face, as in Actinopbrys; but in the groups they commonly project from tbe 

 exterior of the whole only. They are simple, delicate extensions of tbe 

 granular protoplasm of tbe surface of tbe body. From their perfect 

 straigbtness they seem to be rigid ; but they are highly flexible, and at 

 times may be seen to bend in a bunch from tbe rude shock of a passing 

 rotifer, like tbe hairs of a brush from tbe pressure of tbe fingers. 



Each and every individual composing a group is enveloped with its 

 own cloak of transparent homogeneous protoplasm, which is, however, 

 extended upon the bridge-like bands, and also extends in more or less long 

 tapering processes on the pseudopodal rays. Tbe protoplasmic investment 

 is loosely pervaded Avith a multitude of delicate semicircular lines or spi- 

 cules, which are arranged with their convexity tangentially to the bodies of 

 tbe animals, and to tbe rays upon which they extend. Upon the surface 

 of the protoplasmic investment they give a wavy or delicately festooned 

 outline. 



Not unfrequently the interior of the body of some individuals con- 

 tains brownish or reddish balls of variable size, sometimes large, as seen in 

 fig. 4. These I have supposed to be food-balls, and of tbe same nature 

 probably are some of tbe green globules viewed chiefly as pertaining to 

 the structure of the animal 



Occasionally I have observed a group of Raphidiophrys elegans retaining 

 among them large colored balls, as represented in fig. 6, the character of 

 which I did not ascertain, though I supposed them to consist of discharged 

 excrementitious matter. 



Tbe individuals of Raphidiophrys elegans commonly range from 0.033 

 mm. to 0.04 mm. in diameter. Tbe pseudopodal rays extend from 0.1 mm. 

 to 0.2 mm. in length, but occasionally may reach 0.4 mm. The semicircu- 

 lar spicules, which envelope the animals, are about 0.0125 mm in length. 



Raphidiophrys elegans is commonly more active in its movements than 

 Actinophrys sol. The groups move in the same gliding manner, but more 

 rapidly, and they continually change their shape. At first spheroidal, they 

 may become oval or more or less quadrate, then elongate, and become 

 conical, pyriforru, or some other shape. The individuals of a group may 

 approach or recede, break their bridge-like bands or establish others, or, as 

 not unfrequently occurs, the large groups may break into two or more 



