THE OPALINID CILIATE INFUSORIANS. 203 



Measurements of a good-sized individual of the slender form. — 

 Length of bodj', 0.3 mm.; width of body, 0.085 mm.; thickness of 

 body, 0.017 mm.; diameter of nucleus, 0.005 mm. to 0.00.>8 mm.; 

 length, and width of endospherules, first 0.0032 mm. by 0.0012 mm., 

 second 0.004 mm. by 0.001 mm., third 0.0042 mm. by 0.0014 mm. ; cilia 

 line interval, anterior, 0.00275 mm., posterior 0.00375 mm. 



The measurements given by Dobell are different from the above. — 

 Length of body, 0.17 mm., or rather over; width of body, 0.05 mm. at 

 the broadest part of the anterior end; also smaller forms in the 

 shape of a " flattened spindle," say, 0.038 mm. long by 0.013 mm. 

 broad. Figures 171, a and &, are copied from Dobell's plate 2, 

 figures 17 and 18, respectively. The animal figured by Dobell in his 

 figure 17 is much more ohtrigo7ia-Vike than any I have found in the 

 slide sent me. 



This Opalina is defined by its general form, its large nuclei, and 

 especially by its elongated, slender endospherules which lie with 

 their long axes transverse to the length of the body and parallel to 

 its surface, conditions different from that of any other known 

 Opalinid. 



There are in this species both long, slender forms and other 

 broader forms. Some of the smallest individuals show degenerating 

 nuclei and numerous smaller "secondary" (?) nuclei (fig. 171, c). 

 The species seems clearly distinct. Considerations of geographical 

 distribution and of structure have led me to question the relation- 

 ship of this species to the Opalinae. (See p. 260.) 



OPALINA VIRGULOIDEA, new species. 



Type. — United States National Museum Cat. No. 16546. 



Host. — Hyla eximia Baird, four infections, from Mexico. The 

 type infection is from United States National Museum specimen 

 No. 14601, September 1 ; A. Duges collector. 



Fig. 172. — Opalina virgdloidea, from Hyla eximia, X 117 diameters. 



Measurements of a large individual.-^ljength. of body, 0.3 mm.; 

 width of body 0.15 mm.; thickness of body 0.02 mm.; diameter of 

 nucleus 0.0055 mm. to 0.0056 mm. ; diameter of endospherule 0.0015 



