THE OPALINID CILIATE INFUSOEIANS. 129 



This good-sized ZelleHella has a rather characteristic form. Its 

 spherical nuclei are shrunken. Around each nucleus in the cyto- 

 plasm, is a clear, narrow, empty space which seems as if it might 

 have been filled by the nucleus before it shrank, but it may as well 

 be the perinuclear portion of the excretory vacuole. 



This form is perhaps identical with the one last described. The 

 histological condition of the scant material available does not allow 

 detailed study of the nuclei. These are more spherical than in 

 typical ZelleHella opisthocarya. In both body form and spherical 

 nuclei Z. opisthocarya [of Bufo monxiae^ considerably resembles 

 Z. hinghami, a smaller species with its small nuclei usually well 

 back in the bod3^ The relationships are not clear without further 

 study of a better series of well preserved infections. I am, there- 



PiG. 95. — Zelleeiella opisthocabta [of Bnro monxiae], X 460 diameters: the 



DOTTED LINES AROUND THE NUCLEI INDICATE OUTLINES OF THE PERINUCLEAR VACUOLES. 



fore, provisionally merely referring this form from Bufo monseiae 

 to its host as a possibly distinct variety of Zelleriella opisthocarya. 



Z£LLERIELLA OPISTHOCARYA [of BUFO TYPHONIUS], new subspecies <?). 



A specimen of this form has been deposited with the United 

 States National INIuseum as Cat. No. 16493. 



Host. — Bufo typhonius (Linnaeus), two abundant infections from 

 Bahia Solada, Panama, J. F. Bransford, collector. The type infec- 

 tion is from United States National Museum specimen No. 25181, 17 

 mm. lonff. 



° Shrunken. 



