THE OPALIXID CILIATE INFUSOEIANS. 



Measuremen ts. — 



189 



This is the largest Opdlhia known. It is rivaled in bulk only by 

 some of the Cepedeas which, though much shorter, are enough thicker 

 almost to compensate. Cepedea Tonga is the only species approaching 

 it in length and it is not nearly so broad. There is almost complete in- 

 tergradation between these largest forms and O. ohtrigonoidea from 

 other hosts, so that the giant forms may be recognized only as a sub- 

 species. It might even be better to treat them as a fornut. 



Opalina ohtrigonoidea maxima. United States National Museum 

 specimen Xo. 16614, (Figs. 158 and 159.) 



Host. — Bufo halophilus Baird and Girard, many living infections 

 from the vicinity of San Francisco, California, April, 1913; M. M. 

 Metcalf collector. 



Measiirem en ts. — 



These infections show greater diversity in size than those from 

 Bufo horeas. some of the shorter ones seeming to be daughter cells 

 recently come from transverse division. All the individuals in figures 

 158 and 159 are from a single slide from one infection. In a previ- 

 ous paper (Metcalf, 1914) I referred to the nuclear conditions in this 

 Opalirui from Bufo halophilus. saying that in my notes I was tenta- 



