GENUS AMCEBA— AMCEDA PROTEUS. 31 



Proteus difflnens. Miillor: AnimaUula Infusoria, 1786,9, tab. ii, figs. 1-12. — Surriray: Diet. Soi. Nat. L826. 



Vibrio Proteus. Gmelim: Lin. Syst. Nat., ed. 13, 1788, 3899. 



Amiba dircrgcns. Bory: Diet. Clas. 1 1 i .-. t . Nat. 1822, 201. 



Amiba Roesili. Cory: Encyo. Mi'-tli., Hist. Nat. Zoophytes, 1824, 46. — Dujardin: Hist. Nat. Zoophytes, 



Infus. 1841, 232. 

 Amiba Miilleri. Bory: Encye. Moth., Hist. Nat. Zoophytes, 1824,40. 

 Amoeba princeps. Ehrenberg: Abb.. Ak. Wis. Berlin, 1831, 28, 79; Infusionsthierchen, 1838, 120, Taf. viii, 



Fig. x. — Perty: Kenntniss kleinst. Lebensformeu, 1852, 188. — Auerbach: Zeitscli. wissens. 



Zool. 1850, 407, Taf. xxii. Fig. 1-10.— Leidy: Pr. Ae. Nat. Sc. 1874, 14,143. 

 Amiba princeps. Dujardin: Hist. Nat. Zoophytes, Infus. 1841, 232, pi. i, fig. 11. 

 Amoeba vamosa. Fromentel: Etudes Microzoaires, 340, pi. xxviii, tig. 2. 

 Ama:ba communis. Duncan: Pop. Sc. Eeviow, 1877, 233. 

 Amaba chaos. Leidy: Pr. Ae. Nat. Sc. 1878, 99. 

 Amoeba proteus. Leidy: Pr. Ae. Nat. Sc. 1878, 99. 



Species comparatively large, nearly colorless, or more or less black 

 by transmitted light, pale yellowish by reflected light; spheroidal or ovoidal 

 when at rest; very variable and ever changing in shape when in motion, 

 ordinarily ramose, palmate, or radiate; comparatively active, creeping, with 

 a disposition to differentiate into an anterior and a posterior region. Pseu- 

 dopods digitate, simple or branching, and blunt, sometimes tapering and 

 pointed. Posterior part of the body in contraction receding in the advan- 

 cing pseudopods, sometimes assuming a mulberry-like appearance. Nucleus 

 usually single, discoid, habitually posterior. Contractile vesicle usually 

 single and large, habitually behind the former. Ectosarc thinly differen- 

 tiated. Endosarc finely and coarsely granular, with many and varied ele- 

 ments, contributing in its flow to the extension of the pseudopods. 



Size, in the globular form to 0.2 mm.; in the ovoidal form to 0.3 by 

 15 mm.; extended in a dendroid form, occupying a space of 0.5 mm. in length 

 by 0.4 mm. in breadth; in a palmate form 0.5 mm. long by 0.35 mm. broad; 

 in a radiate form from 0.2 mm. to 0.5 by 0.4 mm. ; in an irregularly cylindroid 

 form to 1 mm. long. The largest observed occupied a space of 0.6 by 0.2 

 and 0.35 mm. 



Locality. — Common in the superficial ooze of ponds and ditches almost 

 everywhere, though rarely in large numbers. Ditches below Philadelphia 

 and brick-ponds in the vicinity. Ponds in the neighboring counties, 

 including Delaware, Chester, Montgomery, Bucks, Berks, and Northamp- 

 ton; Broad Mountain, Schuylkill County; Pokono Mountain, Monroe 

 County, Pennsylvania; at Absecom, Hammonton, Woodstown, Vineland, 

 Cape May, and other places in New Jersey; Newport, and Narragansett, 

 Rhode Island ; anil lakes of the Uinta Mountains, Wyoming Territory. 



A large Intuitu is the subject of the earliest notice of a Fresh-watei 



