96 



BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



of nucleus 0.01 mm. ; diameter of endospherule 0.0015 mm. 

 interval, anterior 0.002 mm., posterior 0.003 mm. 



cilia line 



Fig. 63. — Zbllheiblla dbndrobatidis.. from Dendeobates typogeaphds, X 460 diamb- 



TBRS : 0, IN LONGITUDINAL FISSION ; d, IN TEANSVKRSB FISSION, THREE LINES OF 

 INSBBTION OF CILIA ARE INDICATED IN C. 



This form is rather similar to Z. [engystomopsis], but probably 

 is distinct. In my material the nuclei of individuals in fission are 

 each oval or spindle-shaped, while in dividing individuals of Z. 

 lengystomopsis] the nuclei are usually in a much more advanced 



d e 



Fig. 64. — Zellbriella dbndrobatidis, from Dendrobates tinctorius, X 460 diameters : 



e, IS IN TRA.VSVBRSB FISSION. 



condition, each forming daughter cell already showing two sepa- 

 rated, spheroidal, telophase nuclei. In general among the binu- 

 cleated Opalinids comparison of the mitotic phases of the nuclei in 

 individuals of corresponding general condition is one of the safest 

 tests of specific distinctness. 



•I 



