GENUS COLPONEMA. 297 



Heteromita adunca, Mereschk. PL. XV. FIG. 44. 



Body oval, rounded posteriorly, sharply pointed and curved to one side 

 anteriorly, nearly three times as long as broad ; cuticular surface entirely 

 smooth ; endoplasm transparent, finely granular ; flagella slender, inserted 

 at the anterior extremity, the vibratile appendage slightly longer than the 

 body, the trailing one exceeding twice that length ; contractile vesicle 

 conspicuous, situated in the anterior body-half. Length 1-4000". 



HAB. Salt water from the White Sea ; on the surface of infusions 

 (Mereschkowski). Movements quick, tremulous, in a zigzag manner. 



Heteromita cylindrica, Mereschk. 



Body cylindrical, evenly rounded at both extremities, twice as long as 

 broad ; cuticular surface entirely smooth ; endoplasm finely granulate ; 

 flagella slender, the anterior one equalling the body in length, the posterior 

 one about twice as long ; contractile vesicle single, subcentral, very large. 

 Length 1-700". HAB. Salt water: White Sea (Mereschkowski). 



GENUS II. COLPONEMA, Stein. 



Animalcules free-swimming, persistent in shape, irregularly ovate, the 

 anterior extremity pointed and curved to one side, the ventral surface with 

 a broad, subcentral, longitudinal groove or channel ; flagella two in number, 

 the one vibratile and the other trailing, the former inserted at the base of 

 the anterior projection, and in front of the oral aperture, the latter produced 

 from towards the centre of the ventral groove. 



Colponema loxodes, Stein. PL. XV. FIGS. 45 AND 46. 



Body gibbously ovate or subsigmoidal, about twice as long as broad, 

 the anterior extremity pointed, curved towards the left, the posterior 

 extremity more bluntly pointed, sometimes straight and sometimes curved 

 towards the right, thus giving the body a sigmoidal outline ; ventral groove 

 very wide in the anterior region, narrowing as it approaches the posterior 

 termination ; flagella slender, subequal, exceeding the body in length ; 

 endoplasm transparent, granular ; contractile vesicle spherical, centrally 

 located ; endoplast indistinct. Length 1-900". HAB. Fresh water. 



The figures of this singular form, as here reproduced, without descriptive details, 

 are alone published by Stein in his recently issued volume. In the lateral flexure 

 of the anterior region it somewhat resembles the Heteromita adunca of Meresch- 

 kowski. 



GENUS III. SPIROMONAS, Perty. 



Animalcules free-swimming or temporarily attached, soft and plastic, 

 flattened or compressed, twisted spirally on their long axis, bearing two 

 anteriorly inserted subequal flagella, one of which is adherent at will. 

 Inhabiting infusions and water with decomposing organic matter. 



