Stokes.] 5b-/ [Nov. 5, 



Notices of Ncto Fresh -Water Infusoria. By Alfred C Stokes, 31. D. 



{Read before the American philosophical Society, November 5, 1SSG.) 



Mastigamceba longifilum, sp. nov. (Figs. 1, 2, 3, 4). 



Animalcules tepent, very soft and extremely changeable in shape, emit- 

 ting bom all parts of the surface simple lobate pseudopodia, or wave like 

 expansions of the sarcode ; the single antero-terminalflagellum five times as 

 long as the contracted body, about twice as long as the extended zooid; 

 contractile vesicle single, anteriorly placed ; nucleus subspherical, small, 

 situated near the anterior extremity. Length, when contracted, W^o i QCU '> 

 extended, ^J^ inch. Habitat — Standing water, among decaying vegeta- 

 tion. 



The figures (1, 2, 3, 4) show four forms of the same interesting little 

 amoeboid creature. The movements are usually slowly repent, while the 

 flngellum is quite active. The zooid not rarely glides forward without the 

 protrusion of distinct pseudopodia, only changing the form of the body by 

 ii regular expansions and contractions, while on other occasions the 

 unbranched obtuse pseudopodia extend from any or all points of the 

 periphery. 



Anisonema pusilla, sp. nov. (Fig. 5). 



Body subelliptical, less than twice as long as broad, depressed, the two 

 extremities narrowed and obtusely pointed, the ventral surface often 

 slightly concave, the dorsal convex and longitudinally furrowed ; anterior 

 flagellum subequal to the body in length, the posterior or trailing append- 

 age about three times as long as the zooid, both originating near together 

 on the ventral aspect a short distance back of the frontal apex ; pharyn- 

 geal passage minute, but distinct; contractile vesicle apparently single, 

 subcentrally located ; nucleus not observed ; endoplasm frequently en- 

 closing small dark particles, probably food fragments. Length of body 

 ^ z x 57 inch. Habitat — Pond-water. Movements oscillating, not rapid. 



Trentonia, gen. nov. 



Animalcules free-swimming, soft and somewhat changeable in shape, 

 bitlagellate, one flagellum trailing, one vibratile ; frontal border slightly 

 bilabiate ; trichocysts not observed ; otherwise as in Ruphidomonas Stein. 



Trentonia flag ellata, sp. nov. (Fig. 6). 



Body obovate, less than three times as long as broad, the anterior 

 border oblique and somewhat bilabiate, the posterior extremity obtusely 

 pointed ; flagella subequal to each other and to the body in length, one 

 extending arcuately forward, often rapidly and spirally vibrating, ap- 

 parently originating in the oral fossa ; the other taking its origin on the 

 ventral or lower surface a short distance behind the anterior extremity, 



