1894.] 343 [Stokes. 



fimbriated, from six to eight in number, arranged in an oblique row and 

 not projecting beyond the body margin ; contraclile vesicle single, spheri- 

 cal, near the left-hand side of the anterior bodj^-half, in the dorsal aspect, 

 the culicular surface of which it elevates at its systole, and through which 

 it seems to discharge its contents ; nucleus double, the two nodules ovate, 

 one being in the anterior, the other in the posterior body-half, near the 

 left-hand body-margin, and each bearing a laterally attached nucleolus ; 

 anal aperture not observed. Length from yi„ to^'^^ inch. Hah. — Shallow 

 way-side pools in the early spring, near Trenton, N. J. Reproduction by 

 transverse fission. Endoplasm brown. 



This form bears a somewhat close resemblance to Urostyla trichogaster 

 Stokes, but difters conspicuously in its habitat, U. trichogaster being 

 found in infusions of decaying vegetable matters, the present species in 

 the clear, pure waters of the pools of early spring. It also diflFers in the 

 character of the adoral depression which does not include a part of the 

 frontal border of the body ; in the absence of the endoral cilia, and 

 especially in the fewer frontal styles. 



The bo'lj' is exceedingly soft and tiexible, and its motions active. The 

 brown endoplasm is often of a beautiful, transparent golden tint. The 

 favorite food is the algal spores and the other small vegetal objects with 

 which the shallow pools are at this time of the year so well supplied, 

 while the food of U. trichogaster is chiefly animal. 



Acineta corrugata, sp. nov. (Figs. 13, 14, 15).— Lorica ovate or sub- 

 triangular, compressed, the length but slightly exceeding the greatest 

 breadth; lateral margins convex, tapering towards the pedicle and 

 variously crenated, or almost smooth and even ; general surface bearing 

 numerous, irregularly disposed but frequently parallel and centrally con- 

 verging, linear ridges, that vary in number, arrangement and general 

 direction with the age of the lorica, in maturity and in old age the inter- 

 linear spaces becoming exceedingly prominent as inflated, rounded and 

 elongated prominences, the lateral borders of the lorica then being con- 

 spicuously and irregularly crenate ; anterior margin slightly elevated cen- 

 trally, this elevation extending perpendicularly along the subcentral 

 region of the frontal and of the dorsal aspects of the sheath, this in trans- 

 verse, subcentral optical section having a rhomboidal outline, the lateral 

 borders truncate and emarginate ; anterior border of the lorica closed in 

 except for a narrow, slit-like aperture traversing it, and an ovate orifice 

 at each anterolateral margin for the passage of the Aisciculate, capitate 

 tentacles ; frontal region, in surface view, compressed and undulate, or 

 with six oppositely disposed, concave depressions ; pedicle conspicuous, 

 well-developed, hollow and about one-third as long as the lorica ; nucleus 

 apparently broadly ovate and subcentrally located ; endoplasm coarsely 

 granular ; the enclosed animalcule usually nearly filling the cavity of the 

 sheath. Length, including pedicle, -^l^ inch. //a6.— Attached to fila- 

 mentous alg;e in the brackish water of a salt marsh, Coney Island, N. Y, 



The corneous, transparent lorica is exceedingly thin and delicate, vary- 



