OPALINID CILIATE INFUSORIANS — METCALF 



539 



0. chattoni. Nucleolar masses, one to four in number, are found in 

 the nuclei of many species of Opalina, but they are so pressed against 

 the nuclear membrane as to be thin disks, often so thin as to escape 

 casual observation in edge view. They are very different from these 

 noticeable, almost spherical, bodies. 



Measurements, in microns: Body (a) 300 by 155, (6) 220 by 120, 

 (c) nuclei 6.9, 5.8, nucleolus up to 2.7, length of cilia 16. 



OPAUNA NUCLEOLATA SIAMENSIS. new subspecies 



Figure 107 



Type: U.S.N.M. No. 22650. 

 Host: Rana macrodon Dumeril and Bibron. 



A specimen of this host from Siam (U.S.N.M. No. 26225), 172 mm. 

 long, bore many very large Opalmas with nuclei of only moderate size 



Figure m.— Opalina nucleolata siamensis, new subspecies, from Rana macrodon: a-c, X 78; d, X 673. 



and generally a single nucleolus in each nucleus. In size, m the range 

 of shapes, and in the general appearance of the mfection, as well as m 

 the presence of these nucleoli, there is a resemblance to 0. nucleolata 

 from Rana chalconota from Java. The nuclei are smaller, a difference 

 sufficient, perhaps, to justify recognition as a subspecies. 



Measurements, in microns: Body (a) 300 by 140, (6) 200 by 90, (c) 

 100 by 68, id) width of body 95, nuclei 4.7, 4, 4.2, dividing nucleus 5.9 

 by 4.9, length of cilia 10, interval between Imes of cilia 2.9. 



