546 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 87 



subspecies. The Protoopalina stages I have not distinguished from 

 those of 0. larvarum, although more intensive study might succeed 

 in this. The Cepedea stages have smaller nuclei and narrower intervals 

 between the lines of cilia. No broad Opalina stage has been seen nor 

 any seemingly adult stage. Figure 113 shows the sorts of larval 

 stages referred to here. It is not worth while to discuss them 

 without further study. 



In tadpoles of R. catesbeiana Shaw are found opalinids very similar 

 to 0. larvarum and showing similar developmental phenomena. The 

 nuclei in general run smaller, and the orbicular shape, with short, 

 usually curved, posterior point, is found less abundantly, but I am not 

 able to find any specific or subspecific distinction between the forms 

 in R. catesbeiana and those in R. clamitans. 



The opalinids in R. pipiens Schreber and R. palustris LeConte 

 are similar in their developmental phenomena. 



OPALINA SEPTENTRIONALIS Metcalf 



Figure 114 



Host: Hyla septentrionalis Boulenger. Three specimens of this 

 frog from Cuba (U.S.N.M. Nos. 7404, 7478, and 10304) and two 



Figure Ui.— Opalina septeiUrionalia Metcalf from Hyla septentrionalis: a-c, X 78; d, X 673, 



