700 Transactions of the Societij. 



are quickly withdrawii ; anterior flagellum scarcely equalling the body 

 in lenMh, apparently arising from the lower surface a short distance 

 behind the frontal margin ; caudal flagelliform appendage trailing, 

 not equalling the body in length, constant and unchangeable in shape ; 

 contractile vesicle double, spherical, close to the frontal border ; nucleus 

 spherical, subcentrally situated; endoplasm granular, often inclosing 

 numerous yellowish food-particles ; excrementitious matters extruded 

 near the posterior extremity, apparently from the right-hand side 

 only. Length of body 1/1500 in. Habitat: Standing pond water. 



Heteromita granuUfera, sp. nov. Fig. 13. 



Body subspherical, smooth, slightly changeable in shape ; endo- 

 plasm often densely crowded with comparatively coarse, dark-bordered 

 granules ; nucleus and contractile vesicle obscured by the endoplasmic 

 granules ; flagella slender, originating close together at the centre of 

 the frontal border, the anterior subequal to the body in length, the 

 trailing appendage from four to five times as long as the zooid ; anal 

 aperture near the posterior extremity. Length of body 1/3000 in. 

 Habitat : An infusion of decaying Sphagnum with pond-water. 



This differs from H. glohosa (Stein) 8. K., in its somewhat smaller 

 size, its smooth surface, and especially in the comparative length of 

 the flagella, and their point of origin, these appendages in H. glohosa 

 being subequal in length, and arising from a point on the anterior 

 portion of the ventral surface. 



Heteromita tremula, sp. nov. Figs. 14, 15. 



Body elongate, subcylindrical or subfusiform, from four to five 

 times as long as broad, not conspicuously changeable in shape, usually 

 slightly curved toward the ventral surface ; both extremities obtusely 

 pointed, the anterior somewhat the narrower; flagella unequal in 

 length and size, the anterior stout, about one-half as long as the body, 

 the posterior, or trailing, appendage slender, arising at some distance 

 from the anterior border, twice as long as the body ; nucleus appa- 

 rently subcentral ; contractile vesicle near the anterior extremity. 

 Leng'th of body 1/4500 to 1/3000 in. Habitat: Standing pond 

 water. Movements by rapid lateral undulations, with a sudden 

 reversal of the direction of the zooid's forward progression. 



Heteromita stagnatilis, sp. nov. Fig. 16. 



Body cylindrical, three times as long as broad, not noticeably 

 changeable in shape, the surface smooth ; posterior margin rounded ; 

 anterior border convexly truncate ; flagella diverse in length, ori- 

 ginating close together at the frontal margin, the anterior or vibratile 

 appendage less than one-half as long as the body, the trailing about 

 twice the body in length; contractile vesicles several, scattered; 

 nucleus subcentrally located. Length of body 1/2250 in. Habitat: 

 Standing pond water, with Lemna and other aquatic plants. 



