GENUS EUGLYPHA— EUGLYPHA ALVEOLATA. 211 



tractile vesicles, two or three in number, are commonly to be detected in 

 active individuals at the periphery of the intermediate zone of the sarcode 

 body. 



In movement, Euglypha alveolata assumes an erect position, as in the 

 Difflugian Protoplasts, and its pseudopods diverge outwardly from the 

 mouth of the shell. They are exceedingly delicate and filamentous, fork 

 at acute angles, and commonly radiate in straight lines. Not unfrequently 

 a branch may be noticed to bend abruptly in a geniculate manner, and 

 occasionally the bent portion is seen slowly to vibrate. Sometimes a 

 • branch is seen rather suddenly to become tortuous and then retracted. 

 Usually but a few pseudopods, two or three, are projected together, but 

 sometimes a considerable number may be observed. 



The size of Euglypha alveolata varies considerably as it occurs in the 

 same and in different kinds of localities. It is usually largest, or best 

 developed, and mostly provided with spines, when living in the sediment 

 of springs, ponds, ditches, and lakes. The smaller and mostly spineless 

 forms are found among algae and mosses, in swamps, meadows, and similar 

 moist positions; likewise among dripping rocks and about fountains. 



The larger forms, provided with spines, range from 0.125 mm. to nearly 

 0.16 mm. in length and from 0.04 mm. to 083 mm. in breadth. The 

 smaller spineless forms range from 0.03 mm. to 0.09 mm. in length by 

 0.012 mm. to 0.042 mm. in breadth The former appear to possess from 

 six to a dozen or perhaps more teeth to the mouth; the later from four 

 to eight teeth. 



Euglypha alveolata, in its varied forms and conditions of development, 

 is one of the commonest of Fresh-water Rhizopods. Its dead shells are 

 found almost everywhere under conditions which may be or may have 

 been favorable to the life of any species of the class. In the living state, 

 of course, it is to be found only in water, or at least in positions which 

 retain more or less moisture. The smaller, spineless forms occur in many 

 places, especially about the roots of Selaginella apus and other mosses in wet 

 meadows and half-dried marshes, on the borders of ditches and about the 

 roots of trees in damp forests among algas and mosses, on dripping rocks 

 and at the mouths of caves, about fountain basins, and even among mosses 

 in the crevices of brick pavements in shaded damp places in the city of 

 Philadelphia. The larger forms, almost always provided with spines, are 



