220 



BULLETIN 120, UNITED STATES NATIONAL MUSEU.M. 



Fig. 193. — Opalina hi'laxena, form parvixu- 

 n-eata, x 117 diameters. the heavy black 

 lines in the lower right figure indicate 

 the plication of the body. 



Jjost. Hi/la vermicolov LeConte, tadpoles, niuueiuus ijifectiona 



from Woods Hole, Massachusetts, July, 1919; E. C. Just collector. 



Metwurements of a large individual. — LengtR of body 0.2 nun.; 

 width of body 0.16 mm. ; thickness of body, anterior 0.018 mm., mid- 

 dle 0.0248 mm., posterior 

 0.0219 mm.; diameter of nu- 

 clei 0.004 mm. (usual) to 

 0.00475 mm. ; diameter of en- 

 dospherules 0.0016 mm. to 

 0.00175 mm.; cilia line inter- 

 val, anterior 0.0023 mm., 

 middle 0.0036 mm., po.sterior 

 0.005 mm. 



These Opalinas are of the 

 same shape as 0. hylaxena. 

 form orhiculata, from the 

 same lot of tadpoles, but their 

 nuclei are very much smaller. 

 Pending a fuller knowledge 

 of the relation of nuclear size to physiological condition nnd phase 

 of life cycle, it seems best to place the individuals of this 

 sort as a forma under the species hylaxena. 



OPAUNA HYLAXENA, form GEORGIANA, new forma. 



Type. — United States National Museum Cat. No. 16574. 



Host. — Hyla versicolor LeConte, one infection, from United States 

 National Museum speci- 

 men No. 44550, 45 mm. 

 long, from Tate, Georgia, 

 July 4, 1908 ; Howell, col- 

 lector. 



M easurements of a 

 hroad individual. — Length 

 of body 0.192 mm. : width 

 of bodj^ 0.162 mm.; diam- 

 eter of nuclei 0.0031 mm. 

 to 0.0045 mm., mean 0.004 

 mm. ; diameter of endo- 

 spherule 0.0016 mm. to 

 0.00175 mm.; cilia line in- 

 terval, anterior 0.0015 

 mm. 



In this infection some individuals are as broad as the orbiculate 

 and parvinuclcate forms of 0. hylaxena, while others are almost as 

 narrow as the ordinary individuals of this species, but in all indi- 

 viduals the nuclei are small, as in the forma 'parvinucleata. 



Fig. 194. — Opalina hylaxena, form georgiana, X 

 117 diameters. The more marked irregulari- 

 ties OF FORM ARE DUE TO DISTORTION FROM PRES- 

 SURE AT THE TIME THE SPECIilENS WERE KILLED 

 IN THE RECTA OF THEIR HOSTS. 



