112 FRESH- WATER RHIZOPODS OF NORTH AMERICA. 



istic of the genus. It was described and figured by Ehrenberg in the 

 'Infusionsthierchen,' and was first specifically named by him. It was also 

 figured and described under the same name by Perty, and subsequently 

 likewise by Carter and Wallich. 



Perty represents a specimen in which the shell appeal's to be composed 

 of chitinoid membrane incorporated with scattered quartz grains. He 

 also figures and describes another under the name of Difflugia baciUariarum, 

 which appears to be a variety of D. acuminata in which the shell is com- 

 posed of diatoms. 



DIFFLUGIA LOBOSTOMA. 



Plate XV, figs. 1-24; XVI, figs. 25-29. 



Difflugia prottiformis. Carter: An. Mag. Nat. Hist, xviii, 1856, 128. 



Difflugia tricuspis. Carter: An. Mag. Nat. Hist, xviii, 1856, 221, pi. vii, fig. 80. — Ehrenberg: Ab. Ak. 



Wis. Berlin, 1871, 264. 

 Difflugia oblonga. Fresenius: Abh. Senckenb. Naturf. Gesells. ii, 1856-8, 225, Taf. xii, Fig. 43-45. 

 D. Exassula tricunpis. Ehrenberg: Abb. Ak. Wissens. Berlin, 1871, 246, 

 Difflugia lobostoma. Leidy: Pr. Ac. Nat. Sc. Phil. 1874, 79; 1877, 307. 

 Difflugia cnnulata. Leidy: Pr. Ac. Nat. Sc. Phil. 1874, 79. 



Shell ovoid, oval, or nearly spherical, usually composed of quartz- 

 sand, rarely in part or wholly of diatoms or of chitinoid membrane with a 

 few quartz particles; mouth terminal, usually from three- to six-lobed, 

 occasionally more; fundus obtusely rounded. Sarcode colorless, or with 

 the endosarc colored green from the presence of abundance of chlorophyl 

 granules; pseudopods to half a dozen or more, and exhibiting the usual 

 shape and changes as in other species. 



Size. — Ordinarily about 0.12 mm. long and 0.1 mm. broad, with the 

 mouth 0.032 mm. wide. Eanging from 0.08 mm. long by 0.06 mm. broad, 

 with the mouth 0.024 mm. wide, to 0.14 mm. long by 0.128 mm. broad, with 

 the mouth 0.048 wide. 



Locality. — Ponds and ditches in the vicinity of Philadelphia; Swarth- 

 more brick-pond, and ponds on Darby Creek, Delaware County; Morris- 

 ville pond, Berks County; ponds in vicinity of Easton, Northampton 

 County, Pennsylvania; ponds in New Jersey; Spencer pond, Maine; 

 vicinity of Jacksonville, Florida; Fort Bridger and Uinta Mountains, 

 Wyoming Territory. Bombay, Carter; Germany, Fresenius. 



Difflugia lobostoma is one of the most common species, and may 

 be found more or less abundantly in the ooze, or among algse, in ponds and 



