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PEOCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 87 



Tlie number of nuclei in the majority of the individuals of 0. 

 acuminata has been estimated from 6 to 36, and they are arranged 

 in the outer layer of the endosarc. 



At a glance, 0. acuminata resembles Metcalf's 0. carolinensis 

 (1923a) because of similarity in the shape of the body. The latter 



Figure llS.—Opalina acuminata Nie from Kaloula borealis: a. Three individuals showing range of size 

 and form; 6, two individuals showing structure. All X 340. (After Nie.) 



differs from the present species in its larger size (400/li in length, 110m 

 in width), shorter cilia, thicker ectosarc, and smaller nuclei. 



The abruptly acuminated posterior end serves to distinguish the 

 species from 0. obtrigonoidea. 



OPALINA UNDULATA Nie 



Figure 119 



Host: Rana limnocharis Wiegmann, from Nanking, China. 



The body is elongated and corkscrew-shaped. The anterior half 

 is considerably broadened and flattened, while the posterior half 

 is greatly narrowed and twisted or spirally plicated into three "undu- 



