GENUS PAMPHAGUS— PAMPHAGUS MUTABILIS. 191 



PAMPHAGUS MUTABILIS. 



Plate XXXIII, figs. 1-9. 



Corycie. Dujardin : An. Sc. Nat. 1852, xviii,240. 



Pamphagus mutabilis. Bailey: Am. Jour. Sei. Arts, 1853, xv, 341. — Archer: Quart. Jour. Mic. Sc. 1871, 



si, 101; 1872, xii, 195,423.— Leidy : Pr. Ac. Nat. Sc. 1878, 172. 

 Corycia (Dujardin). Claparede and Lachmann : ittudes lulus, et Eliiz. 1858-59, i, 453. — Pritcliard: Hist. 



Infus. 1861, 550.— Leidy : Pr. Ac. Nat. Sc. 1874, 227. 

 Pamphagus (Bailey). Pritcliard: Ibidem, 551. 

 Corycia Dujardini. Gagliardi: Quart. Jour. Mic. Sc. 1871, xi, 80. 

 Plagiophrys scuiiformis. Hertwig and Lesser: Archiv mik. Anat. 1874, x, Suppl. 115, Taf. 3, Fig. 2. 



Animal compressed ovoid, ovate, or sub-pyriform ; lateral borders ex- 

 tending to the fundus, acute; fundus in the greater breadth obtusely rounded, 

 more or less acute or even acuminate; mouth small, transversely oval, with 

 a thickened border. Sarcode pale granular, colorless, or faintly yellowish, 

 with diffused minute oil molecules, often with darkly defined oil-like glob- 

 ules in the upper region, and frequently water vacuoles in the lower region. 

 Nucleus large, clear, compressed spherical. Food usually of various one- 

 celled alga?. Animal in movement upright, with the mouth downward, 

 and the pseudopods divergent and spreading horizontally ; at rest, lying 

 upon the broader sides. 



Size. — Ranging from 0.04 mm. long by 0.028 mm. in the greater breadth 

 to 0.1 mm. long by 0.068 mm. in the greater breadth. 



Locality. — The ooze of springs and ponds, and pools in sphagnous 

 swamps. Observed in Pennsylvania, New Jersey, and Fort Bridger, Wyo- 

 ming Territory. 



Dujardin described a rhizopod under the name of 'Corycie,' in 1852, 

 from specimens found in rain-water, expressed from Jungermannia, collected 

 in November and December. He observes that it is a very remarkable 

 Amoeba, on account of its membranous integument, which folds in various 

 directions, according to the movements and contractions of the animal, and 

 frequently presents the appearance of being twisted when it turns on itself. 

 The membranous envelope is perfectly extensible and elastic. The size of 

 the animal is from 0.08 mm. to 0.2 mm. 



The following year, Professor Bailey described what seems to be the 

 same animal under the name of Pamphagus mutabilis. It was found in great 

 number in an aquarium which had been supplied with material from pools 

 and streams in the vicinity of West Point, New York. Bailey adds: "I 



