82 



BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



This small Protoopalina is distinguished by its very slender, taper- 

 ing, posterior end, almost like a microgamete mother cell. The cilia 

 are longer in front and diminish in length through the middle third 

 of the body, being absent from the slender, tail-like posterior third. 

 There are four distinct ellipsoid nuclei, each showing eight chromatin 

 masses, which might indicate either eight or four as the number of 

 the massive chromosomes. One individual was found with three 

 nuclei (fig. 51, c), one being very large and in an earlier mitotic 

 stage, almost a reticulate condition, there being still about eight large 

 chromatin granules, while the anterior nucleus had already divided 

 into two smaller daughters which, however, were still connected by 

 a thread. In each of these were obscurely seen a smaller number of 

 chromatin masses, not more than four. There therefore seem to be 

 four true massive chromosomes. The nuclei shown in figure 51, a. 



Fig. 51. — Protoopalina quadeinuct.eata, X 460 diameters. 



are in about an equatorial plate stage of mitosis. (The equatorial 

 plate in the Opalinids is never definite and regular.) Figure 51, a, 

 does not attempt to show the number of the chromatin masses, not 

 all being drawn. Figure 51, c, shows an individual recently come 

 from transverse division. The anterior nucleus is already divided 

 into two daughter nuclei. The posterior nucleus is apparently not 

 normal, being unusually large and still undivided. The posterior 

 end of the body has not yet taken on the regular form with a slender, 

 elongated, naked tail. 



This is a very distinct species, not likely to be confused with any 

 other. 



PROTOOPALINA AXONUCLEATA, new species. 



r?/;?e.— United States National Museum Cat. No. 16458. 

 Host. — Bufo hufo asiaticus (Steindachner), three infections in 

 United States National Museum material. The type infection, in 



