110 



BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



32 mm. long, and one other, from Urubamba, Peru, 9,500 feet alti- 

 tude, July 15, Yale Peruvian Expedition, collectors; and another 

 scant infection from United States National Museum specimen No. 

 48560, 23 mm. long, from Cuzco, Peru, 11,500 feet altitude, July 9, 

 Yale Peruvian Expedition, collectors. 



Measurements of an ordinary individual. — Length of body 0.093 

 mm. ; width of body 0.0465 mm. ; diameter of nucleus 0.014 mm. ; 

 cilia line interval, anterior 0.002 mm. ; posterior 0.00312 mm. 



c d 



Fig. 76. — Zellekiella binghami : a, h, and d, cells of the ordinaky sort, X 460 

 diameters; c, a cell entering upon mitosis, as indicated by the slight elonga- 

 tion OF THE nuclei, X 1,000 DIAMETERS. 



This small Zelleriella is in general of the form shown in the 

 figures, though some rather broader individuals are seen. All the 

 individuals observed in my material have two spheroidal nuclei, 

 except a few in which the nuclei are just a little elongated (fig. 

 76, c). In two of the latter sort, six chromatin masses were ob- 

 served in each nucleus, which suggests that there are probably six 

 macrochromosomes, but one can not be confident of this without 

 studying the mitotic cvcle, especially the anaphase, and my material 

 does not allow this. I do not understand the huge chromosome in 

 the posterior nucleus shown in figure 76, c. 



