10 Transactions. — Zoology. 



single, sub-central. Endoplast not observed. All details are 

 extremely difficult of observation, on account of tbe immense 

 number of black globular particles apparently filling the body. 

 Motion rapid, rolling on the longer axis. 



A kind of temporary encystment is frequently to be observed 

 in this species : the animalcules encyst themselves without 

 apparently any particular object, protective or reproductive. 

 An animalcule will slacken the speed of its progress through 

 the water, the motion becoming slower and slower, but very 

 gradually ; as it approaches a state of rest it will become quite 

 spherical and surround itself with an apparently mucous, 

 translucent, globular sheath. After perhaps half or three- 

 quarters of an hour all motion will have ceased, except that of 

 the cilia, which slowly vibrate. After awhile (from a few 

 minutes to an hour) the rolling motion will gradually recom- 

 mence, become by degrees more and more rapid, and at length 

 reach again the normal speed ; the animalcule regains its 

 elliptical form and travels as before until it chooses to repeat the 

 process just described. The object of these proceedings isnotclear. 



Length, r i^ inch = 200 ft. 



Otaki, Hutt Valley, Wellington, W. M. MaskeU. 



A peculiar species, of large size ; approaching in its pyriform 

 aspect somewhat Trachelitis ovum ; but the black particles prevent 

 any observation of vacuolar reticulations. Trachelitis also seems 

 never to present an evenly elliptical form. 



Order. Heterotricha. 



Genus Stentor. 



Stentor attenuates, sp. nov. Plate II., fig. 15, a, b, c. 



Body very highly extensile ; colour blueish-green ; conspi- 

 cuously striated ; excessively slender when fully extended, the 

 stem often becoming as thin as the pedicle of a VorticeUa. 

 Peristome narrow, wine-glass shaped, small, the edge scarcely 

 or not at all recurved ; edge irregular or wavy, with a small 

 spiral involution. Parenchyma containing several dark granular 

 masses. Contractile vesicle single, situated below the peristome 

 edge, often exhibiting a short attached canal. Endoplast monili- 

 form. Peristomal cilia long ; the body and stem clothed with 

 short fine cilia. Body when free- swimming usually elongate 

 (fig. '15, b), pointed posteriorly, conspicuously striated, exhibit- 

 ing the spiral involution of the peristome ; sometimes globular 

 (fig. 15, c). A commencement of reproduction by fissure was 

 observed on one occasion in the fringe, shown in fig. 15 at d. 



Length of peristome (average), -^ inch = 417 /i ; width, 

 J,, inch — 312 /u. Length of stem when fully extended reaching 

 sometimes £ inch = 3125 /u. 



Wellington, C. I'. Pontes. 



