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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 87 



The layer of ectosarc is rather thick and consists of very large and 

 prominent alveoles. The endospherules in the endosarc are large, 

 being ellipsoidal, rounded, or pear-shaped. 



Measurements for a number of specimens, in microns: Length of 

 body 238-428.4, width 22.8-36.1; length of nucleus 22.8-26.6, width 



Figure Z6.—Protoopalina limnochans: a, Structure of the animal, X ca. 250; 6, cross section, posterior to 

 the midregion, X ca. 500; c, two young animals soon after binary fission, X ca. 250. (After Nie.) 



9.5-13.3. The measurements of some of the endospherules show the 

 average length to be 2.7;u, and the average width 0.9/i. The meas- 

 urement of the ciUa line interval of one animal was 1.9/x on the ante- 

 rior end and 3.4/i on the posterior end. 



This species seems to be closely related to Protoopalina filiformis 

 Metcalf (1923a). It differs from the latter mainly in number of 

 nucleoli (6 in P. filiformis). The body is more flattened and the 

 endospherules are much larger as compared with P. filiformis. 



PROTOOPAUNA PINGI Nie 



Figure 37 



Host* Rana plancyi Lataste, from Nanking, China. 



This species is relatively small. The body is somewhat spindle- 

 shaped, the posterior end being narrow or sharply pointed while the 

 anterior end is somewhat narrow and rounded. The animal is usually 



