230 FRESH-WATER BIOLOGY 



1 18 (117) Margin of neck not dentate. Sphcnoderia 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 

 [■t>.'.-i&}yy points opposite each other. Pscudopodia are numerous and very long. 

 %-lji Habitat sphagnum. Length from .s5 to 50 ti. Leidy describes a species 



under the name 5. macrolcpis, dilTering from other species by the angular 

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



^ '"'~' FiG.^31. Sphenoderia lenta. a, contractile vacuole. X 300- (.\fter 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. 



AssiiUna Ehrenberg . . 123 



123(124) Large size, rounded l552///«a 5ewJww/MW Ehrenberg 1848. 



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

 tractile vacuole single. Nucleus very large, elliptical. Pseudopodia 

 •MP -yu\ seldom observed. Common in sphagnous swamps. Length 60 to 



Fig. 332 Assulina seminidum. cv, contractile vacuole. X 290. 

 (After Leidy.) 



124(123) Small size, oval l552///;/(Z ;;?/;?or Penard i8qo. 



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

 l-«Tjf.xi|A the aperture is more regularly crenulate. The hexagonal design formed by the 

 MM]1 imbricating plates is very symmetrical. Found among mosses. Length 35 m- 



w'tvi 



^^''^'''^ Fig. 333. Assulina minor. X 30°- (.^fter Penard.) 



125 (122) Plates round or oval; margin of aperture with prominent denticles. 

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



126(133) Aperture circular 127 



127 (130) Spines at apex only 128 



128(129) Spines, one or two Euglypha mucronata Leidy iSjS. 



The shell not compressed; plates imbricating, arranged in 

 ^________,.^_^^ longitudinal, alternating rows. The_ fundus tapers to a point 



'r^^^^f^^i^_^^'^^'y^'^^:^^^ which is provided with one or two spines. Found in sphagnous 



"^j^^^^i^D^'l^X--.^ ' swamps. Reported from North America only. Length 108 to 



Fig. 334. Euglypha viucronala. X 165. (After Leidy.) 



129(128) Spines in a tuft Euglypha cristata Leidy iSy 4. 



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

 as in preceding species. Pseudopodia rarely extended. Habitat 

 i^i^,^, sphagnous swamps. Length 33, to 84 m- 



'-^'"^ ^' Fig. 335. Euglypha cnsiata. X 425- (After Leidy.) 



130 (127) Spines not at apex only 131 



