198 FRESHWATER RHIZOPODS OP NORTH AMERICA. 



inferior. Sarcode mostly colorless, with a large clear nucleus, but usually 



with other constituents of the former obscured by the nature of the shell. 



Pseudopods numerous, exceedingly delicate, filamentous, and forking at 



acute angles. 



PSEUDODIFFLUGIA GRACILIS. 



Plate XXXIII, figs. 18-28. 



Pseudodifflugia gracilis. Schluniberger : An. Sc. Nat. 1845, iii, 254. 



Pleurophrys sphcerica. Claparede and Lacbmann : Etudes Infusoires et Rhizopodes, 1859, i, 455, pi. xxii, 

 fig. 3. — Archer: Quart. Jour. Mic. Sc. 1869, pi. xx, fig. 1, 1870, 121. — Hcrtwig and Lesser: 

 Arch. mik. Anat. 1874, x, Suppl. 135, Taf. iii, Fig. 4.— Schulze : Ibidem, 1875, xi, 122. 



Pleurophrys? amphitremoidcs. Archer: Quart. Jour. Mic. Sc. 1870, 121, pi. xx, fig. 2. — Schulze: Arch, 

 mik. Anat. 1875, xi, 123, Taf. vii, Fig. 1. 



Pleurophrys? fulva. Archer: Ibidem, 1870, 122, pi. xx, fig. 3. — Schulze: Ibidem, 124, figs. 2, 3. 



Pleurophrys comprcssa. Schulze : Arch. mik. Anat. 1875, xi, 125, Taf. vii, Fig. 4, 5. 



Pleurophrys lageniformis. Schulze: Ibidem, Fig. 6-8. 



Pleurophrys angulata. Mereschkowsky : Arch. mik. Anat. 1878, 192, Taf. x, Fig. 14. 



Shell of variable form, mostly spheroidal, ovoidal, or oblong oval, and 

 of uniform transverse diameters, but rarely somewhat compressed, usually 

 straight, occasionally slightly curved. Mouth terminal, circular. Structure 

 of the shell mostly obscurely granular, often with fine sand, and frequently 

 almost or quite entirely composed of coarser sand ; colorless or brownish. 



Size. — Length from 0.04 mm. to 0.16 mm.; breadth 0.02 mm. to 0.1 mm. 



Locality. — Frequent in the ooze of ponds, ditches, etc. Vicinity of 

 Philadelphia and other places in Pennsylvania; New Jersey; Uinta Mount- 

 ains, Wyoming Territory. 



The genus Pseudodifflugia is one of those described by Schlumber- 

 ger,* and not usually recognized by succeeding observers. It is character- 

 ized as having a membranous shell, ovoid or ovo-globular, smooth or rolled, 

 with a wide round aperture, from which project very long fine filaments, 

 simple and branched. The author remarks that the genus approaches 

 nearly to Difflugia, but differs in the character of its pseudopods. 



The species Pseudodifflugia gracilis is described as having an ovoid, 

 bluish brown shell, of variable length, and encrusted as it were with minute 

 grains of sand. The size is 0.035 mm. to 0.056 mm in length by 0.029 mm. 

 to 0.035 mm. in breadth. 



. The characters assigned to Pleurophrys by Claparede and Lachmann 

 lead me to suspect that it is not different from Pseudodifflugia. They 

 observe that it is related with the Actinophryans as Difflugia is with the 



* Annales des Sciences Naturelles, 1845, 254. 



