New Species of Rotifera and Protozoa. 315 



same diameter throughout, or sHojhtly dilated at oral 

 opening. Sides straight, more than twice as long as 

 wide. 



This species agrees very closeh' with T. heroidea Stein, 

 and I place it here provisionally until its minute struc- 

 ture can be more closely studied. The shape of the 

 lorica is characteristic: long, narrow, with straight sides, 

 often slightly dilated at the mouth, and frequently with 

 a bluntly conical fundus, giving it the shape of a rather 

 long thimble. It is smaller than T. heroidea\ its aver- 

 age length being .059 mm. and the average width .029 

 mm. 



It was found in April and .May, in company- with 

 Codonelia cratera Leidy, in tows from the Illinois River, 

 Thompson's Lake, and Quiver Lake. 



Opercularia irritahUis n sp. 



(Plate XXV :., Fig. 17 and 18.) 



Body ovate, elongate, truncated posteriorly, two 

 and a half times as long as wide. Greatest diame- 

 ter in front of the middle, from whence the sides slope 

 gradually from the posterior end. Peristome border 

 everted, thickened, forming a conspicuous ridge or ring; 

 constricted below the border. 



Ciliary disc slightly dome-shaped, not highly elevated; 

 two rows of cilia present. The cuticular surface is 

 smooth. Endoplasm granular, yellowish. Contrac- 

 tile vacuole large, circular, placed in the anterior 

 part, near the peiistome. Nucleus band-like, curved, 

 placed transversely in the anterior part of the body. 



The zooids are very sensitive, and when contracted 

 they have an oval shape; the anterior part is projected 

 into a snout-like prominence and thrown into numerous 

 longitudinal folds; while the posterior part is contracted 

 around the base of the pedicle, and thrown into trans- 

 verse plications. The membranous collar is not very 

 conspicuous. The phar^'nx is large, extends half the 



