THE OPALINID CILIATE INFUSORIANS. 



181 



Measurements of a large individual. — Length of body O.-ll mm.; 

 width of body 0.117 mm. ; thickness of body 0.0325 mm. ; diameter of 

 nucleus 0.0045 mm. to 0.006 mm.; diameter of endospherule 0.002 

 mm. ; cilia line interval, anterior 0.00175 

 mm., middle 0.001 mm., posterior 0.004 mm. 



These Opalinas are like O. ohtrigonoidea, 

 but a good many of the individuals have 

 the posterior end of the body more slender 

 than we find it in any other infections of 

 this species studied, and its nuclei are 

 smaller. It is very like some of the smaller 

 individuals from Bufo foxoleri., but there 

 is much less diversity of form than in the 

 latter specimens. . It does not deserve treat- 

 ment as a distinct subspecies. 



Opalina ohtrigonoidea, United States 

 National Museiun No. 16543. 



Host. — Hyla arenicolor Cope, one abun- 

 dant infection, from United States Na- 

 tional Museum specimen No. 19726, 46 mm. 

 long, from Fort Huachuca, Arizona, 1892'; 

 T. E. Wilcox, collector. 



Measurements of an ordinary individual. — Length of body, 0.444 

 mm.; width of body, 0.12 mm.; thickness of body, anterior, 0.0385 

 mm., middle, 0.045 mm., posterior, 0.0385 mm.; diameter of nucleus 



0.00475 mm. to 0.006 mm. (0.005 mm. 

 mean) ; length and breadth of endo- 

 spherule, first 0.0015 mm. by 0.00125 

 mm., second 0.00175 mm. by 0.0015 mm. ; 

 cilia line interval, anterior 0.00235 mm., 

 middle 0.004 mm., posterior 0.004 

 mm. 



Fig. 147. — Opalina obtrigonoi- 

 DBA, FBOM Hyla arenicolor, 



X 117 DIAMETERS. 



Opalina ohtrigonoidea^ United States 

 National Museum No. 16544. 



Host. — Hyla pickeringii (Holbrook), 

 one abundant infection, in United States 

 National Museum specimen No. 3604, 

 20 mm. long, from Aux Plains River, 

 Illinois ; R. Kennicott, collector. 



Measurements of a large individ- 

 v.aJ. — Length of body, 0.444 mm.; 

 width of body, 0.09 mm. ; thickness of body, anterior, 0.028 mm., mid- 

 dle 0.048 mm., posterior, 0.0358 mm. ; diameter of nucleus, 0.004 mm. 



Fig. 148. — Opalina obtrigoxoi- 

 DEA, FROM Hyla pickeringii, 



X 117 DIAMETERS. 



