OPALINID CILIATE INFUSORIANS METCALF 



485 



Nucleoli seemingly 6, but they were not observed in anaphases of 

 mitosis, where they are most easily and reliably counted. The 

 second individual shown in the figure (fig. 39, b) seems almost a Pro- 

 toopalina and represents, doubtless, a Protoopalina stage in the de- 

 velopment. The species is probably brasiliensis, the usual one found 

 in Leptodadylus ocellatus, but study of more material would be neces- 

 sary to determine. The Cepedea present in the same tadpole is de- 

 scribed on page 512. There are in the infection a number of individuals 

 that are abnormal, as indicated by one of their two nuclei staining 

 uniformly dark with Delafield's haematoxylin (fig. 39, b). 



ZELLERIELLA URUGUAYENSIS. new species 



Figure 40 



Type: U.S.N.M. No. 22627. 



Host: Bufo arenarum Hensel. Five specimens from Montevideo 

 were infected; 16 from the same locality carried a huge Zelleriella up 

 to four times as large (linear dimen- 

 sions) as Pinto's Z. brasiliensis, with 

 which it might carelessly be confused. 



The largest specimens of Pinto's 

 species (I have studied his slides) are 

 much smaller than the smallest from 

 B. arenarum, and the nuclei are situ- 

 ated farther back in the body. The 

 largest individuals of Z. magna, from 

 Venezuela, in Leptodadylus typhonius 

 (Daudin) are as large as the smallest 

 specimens in B. arenarum, but the 

 shape is very different. The largest 

 Z. opisthocarya, from Nicaragua, in 

 B. coniferus Cope are as large as 

 medium-sized specimens from B. 

 arenarum and they agree in shape, 

 and the position of the nuclei is usually well back on the body, but the 

 nuclei are but half as large as in the Montevideo species. This is 

 clearly distinct. 



Measurements, in microns: 



Figure 40.~ZeUeriella uruguayensis, new 

 species, from Bufo arenarum, X 59. 



Measurement 



Body length 



Body width 



Nucleus length 



Dividing, 

 4 nuclei 



338 



401 



55 



Large 



441 



247 



65 



Medium 



327 



195 



44 



Small 



245 

 140 

 25. 7 



The nucleoH are probably 6 in number. 



