224 



59 (72) 



60 (6i) 



Fig 300. 

 X no. 



61 (60) 



62 (69) 



63 (66) 



64 (65) 



FRESH-WATER BIOLOGY 



Shell without internal partition or diaphragm. 



Difflugia Leclerc . . 60 



Aperture not central Difflugia constricta Ehrenberg 1841. 



Shells of various forms from nearly spherical to oval and elon- 

 gate. Aperture always eccentric. Pseudopodium single, rarely 

 observed. Spines sometimes developed from the fundus. This 

 :iccaaii>' species is closely related to Centropyxis aculeala. A common 



species, widely distributed. Large forms may reach 200 m m 

 Difflugia constrict. I. length. Most individuals are very much smaller. 

 (After Leidy. ' 



Aperture central 62 



Shell typically spherical 63 



Margin of aperture smooth 64 



Neck deeply constricted; aperture small, with margin always re- 

 curved Difflugia urceolata Carter 1864. 



This species is without spines, but a variety, D. urceolata var. 

 olla, may possess a few short stubby spines developed from the 

 fundus. The protoplasm does not fill the shell. Pseudopodia 

 numerous; nuclei many. Found in the ooze of pond water. Large 

 forms reach a length of 350 ix. 



V^?:=;?Clb Fig. 301. Difflugia urceolata. X 75- (After Leidy.) 



65 (64) Neck, when present, not deeply constricted;- aperture wide, with 

 margin seldom recurved. . . . Difflugia lehes Penard 1893. 



In many respects this species resembles the preceding one. 

 The thin, recurved collar is sometimes present but the aperture 

 is much larger. The shell is very fragile. Nuclei sometimes more 

 than 100. Found in ooze at the bottom of ponds, lakes, etc. 

 Very large, some reaching 400 m in length. 



Fig. 302. Difflugia lebes. X 60. (After Penard.) 



66 (63) Margin of aperture not smooth 67 



67 (68) Margin with numerous teeth. . . . Difflugia corona Wallich 1864. 



Shell composed of large sand grains but ver>' smooth and regular 

 in outline. Teeth usually more than twelve in number, very evenly 

 arranged. Nucleus single. Pseudopodia numerous and large. 

 From six to nine spines usually developed from the fundus. A very 

 common species in ooze of ponds. Length, with spines, 200 to 250 /*• 



Fig. 303. 



lugia corona. Oral view. X 90. (After Leidy.) 



68 (67) Margin with few blunt lobes. . . . Difflugia lohostoma Leidy 1874. 



Shell ovoid or nearly spherical, usually with a quadrilobate aper- 

 ture. However, the lobes are somewhat irregular, a trilobate aperture 

 sometimes appearing. Pseudopodia few. Found among algae and in 

 the ooze of ponds; common. Average length 150 m- 



Fig. 304. Difflugia lobostoma. Oral view. X 105. (After Edmondson.) 



69 (62) Shell never spherical 70 



