Peb., 1920] The Protozoa of Mirror Lake 119 



stone near the outlet of the larger pond (Station K), and on 

 alga-covered poplar roots at Station D. The animal darts 

 in such an extremely erratic manner as to defy examination. 

 Fortunately, it has the habit of temporarily attaching itself 

 by the posterior end and becoming somewhat quiescent, but 

 even then it rotates on the longitudinal axis. 

 Length 63ai- 



Strombidium typicum (Lankester). 



An individual was found in each of the two collections 

 made in January, one of alga-covered poplar roots (Station D) 

 and one of algae from the submerged stone (Station G) very 

 close by. 



Length 126^. 



Halteria grandinella (Miiller). 



Several individuals were taken on alga-covered poplar roots 

 (Station D), collected during December and January. On 

 March 1, the form w^as common in sediment taken from the 

 stone near the outlet of the larger pond (Station K) . . 



Length 48^1. 



Strombidinopsis sp.? PI. Ill, Figs. 3 and 3a. 



One individual was found in algae from a submerged stone 

 at Station G, on December 3. It was free swimming, vase- 

 shaped and nearly six times as long as broad. The anterior 

 margin was flaring and obliquely truncate; the cilia of the 

 peristome were very long, powerful and bent forward, forming 

 a spiral wreath of two turns, which extended into the oral 

 fossa. Posteriorly the cell was broadly rounded and terminated 

 in a short conspicuous, eccentric acumination. The cilia of the 

 cuticular surface were short, sparse, fine and arranged in 

 longitudinal rows. The cell was hyaline and the animal's 

 movements were rapid. 



Length llS^t. 



Family Tintinnidce. 



Tintinnidium fluviatile (Stein) . 



On March 22, one individual of this species was found on 

 algae from the submerged stone at Station G. The lorica 

 contained many foreign particles which made it appear rough. 



