Protozoa and Rotifera at Havana, III. 333 



Suborder SPIROTRICHA. 



Section Heterotricha. 



Family PL.AGIOTOMID.ffi. 



CONCHOPHTHIR^US &TEIN. 



Colorless, not elastic, strongly compressed, in lateral view 

 oval; mouth usually near the middle of the ventral edge, 

 which is here sinuated because of the more or less excavated 

 trough-like peristome-field ; ciliation uniform, cilia rather 

 long, usually a few larger ones along the anterior edge of the 

 peristome-field and at the posterior extremity. 



62. C. anodontae Ehrbg. 



Among the gills of Unio anodontoides from the river in 

 July. Found also in other Unionidas. 



Spirostomtjm Ehrbg. 



Colorless or green, elongate, often very much so, very 

 elastic and flexible, rarely compressed ; peristome-field nar- 

 row and long, extending from near the anterior end nearly 

 straight to the mouth, with a zone of adoral cilia upon its 

 left margin, turning obliquely into the mouth ; ciliary stria- 

 tion very distinct, and slightly oblique ; dorsally a long, 

 canal-like extension from the large contractile vacuole at the 

 posterior end. 



63. S. teres C. & L. 



Found only once, in August, in a towing from Quiver Lake. 



Family STENTORID-ffi. 



Stentor Oken. 



Fixed or free-swimming at will ; trumpet-shaped when ex- 

 panded, tapering to the attached posterior end, the anterior 

 end broad and flattened, occupied entirely by the peristome- 

 field, which is encircled by the adoral zone of cilia ; this takes 

 a slightly spiral course on the ventral edge of the peristome- 

 field, descending into the pharynx; ciliation of body very 



