88 



BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



Measurements: A^ of a large individual; B^ of a small indi- ^ 

 viduM — 



Measurements. 



Length of body 



Width of body 



Diameter of endospherule 



Length of nucleus 



Width of nucleus 



This large Zelleriella is quite constant in form, being of much the 

 same shape as Opalina ranarum. In the smaller individuals the 

 nuclei are nearly spherical and are often united by a thread. The 



largest forms show two distinct, 

 more ellipsoidal nuclei doubtless 

 preparing for mitosis. My mate- 

 rial is not well enough preserved 

 for detailed study of the nuclear 

 phenomena, nor can one clearly 

 see the endospherules, or the cilia 

 and their lines of insertion. 



ZELLERIELLA [ATELOPODOS], new 

 species (?). 



A specimen of this form has 

 been deposited with the United 

 States National Museum as Cat. 

 No. 16462. 



Host. — Atelopus varius Stannius, 

 one scant infection, in United 

 States National Museum specimen 

 No. 30633, 38 mm. long, from Pico 

 Blanco, Costa Rica; W. M. Gabb, 

 collector; no date. 



Measurements. — Length of 

 body 0.1575 mm.; width of body 

 0.1015 mm.; diameter of nucleus 0.019 nam.; diameter of endo- 

 spherule not clear; cilia line interval, anterior 0.0015 mm., posterior 

 0.0025 mm. The number of massive chromosomes can not be de- 

 termined from the material available. 



This species has much the same form as Z. hypopacheos, but the few 

 individuals I have show two distinct spherical nuclei, not connected 

 by a thread as in specimens of Z. hypopacheos of the same size, nor 

 ellipsoidal as are the nuclei of the larger specimens of Z. hypopacheos. 

 This different mitotic condition of the nuclei suggests that Z. 

 [atelopodos'] is a distinct species, but I prefer not to name it definitely 



Fig. 54. — Zelleriella hypopacheos, X 



4C0 DIAMETERS. IN THIS AND IN SUBSE- 

 QUENT FIGURES THB TWO DOTS OUTSIDE 

 THE CONTOUR OF THE BODY INDICATE THE 

 LIMITS OP THE ANTERIOR END. 



