230 



FRESH-WATER BIOLOGY 



118 (117) Margin of neck not dentate. Sphenoderia lenta Schlumberger 1845. 



Shell ovoid or rounded with large, round imbricating plates. The aper- 

 ture consists of a narrow, elongated opening, extending between two lateral 

 points opposite each other. Pseudopodia are numerous and very long. 

 Habitat sphagnum. Length from 35 to 50 /* Leidy describes a species 

 under the name S. macrolepis, differing from other species by the angular 

 plates composing the shell. Habitat sphagnum. Length 24 to 39 p. 



FIG, 33 1. Sphenoderia lenta. cv, contractile vacuole. X 300. (After Leidy.) 



119(116) Shell compressed, without a neck 120 



120 (137) Aperture terminal. 121 



121 (136) Margin of aperture dentate 122 



122 (125) Plates elongate-elliptical ; margin of aperture finely dentate. 



Assulina Ehrenberg . . 



123 (124) Large size, rounded. 



123 



Assulina seminulum Ehrenberg 1848. 



Adult forms of this species are chocolate brown in color. Con- 

 tractile vacuole single. Nucleus very large, elliptical. Pseudopodia 

 seldom observed. Common in sphagnous swamps. Length 60 to 

 88 M. 



FIG. 332 Assulina seminulum. cv, contractile vacuole. 

 (After Leidy.) 



X 290. 



124 (123) Small size, oval. 



Assulina minor Penard 1890. 



This species is also brown in color but clearer than the preceding one and 

 the aperture is more regularly crenulate. The hexagonal design formed by the 

 imbricating plates is very symmetrical. Found among mosses. Length 35 ^. 



FIG. 333. Assulina minor, x 300. (After Penard.) 



Plates round or oval; margin of aperture with prominent denticles. 

 Spines often developed. . . . Euglypha Dujardin . . 126 



Aperture circular 127 



Spines at apex only 128 



Spines, one or two Euglypha mucronata Leidy 1878. 



The shell not compressed; plates imbricating, arranged in 

 longitudinal, alternating rows. The fundus tapers to a point 

 which is provided with one or two spines. Found in sphagnous 

 swamps. Reported from North America only. Length 108 to 

 140/1. 



FIG. 334. Euglypha mucronata. X 165. (After Leidy.) 



129(128) Spines in a tuft Euglypha cristata Leidy 1874. 



Shell elongated, very little compressed if any, with plates arranged 

 as in preceding species. Pseudopodia rarely extended. Habitat 

 sphagnous swamps. Length 33 to 84 M . 



FIG. 335. Euglypha cnstata. X 425- (After Leidy.) 



130 (127) Spines not at apex only 131 



125 (122) 



126 (133) 



127 (130) 



128 (129) 



