OPALINID CILIATE INFUSORIANS METCALF 



545 



behind, named at that time 0. larvarum. These flat, posteriorly- 

 pointed forms have 8 or more, generally less than 20, nuclei. They 

 seem to be individuals precociously developed by flattening of 

 "Cepec^ea-larvae" before they have lost their posteriorly pointed 

 shape. 



Brumpt (1915) desciibed retrogressive development of opalinids in 

 the tadpoles, resulting in the formation of cysts that are capable of 

 infecting tadpoles again. I have not traced out this process. Miss 

 Cowles has described the course of development of 0. virguloidea in 

 Rana sylvatica (p. 556). 



OPALINA (?) 



Figure 113 



In addition to undoubted 0. larvarum from tadpoles of R. clamitans 

 Latreille there are larval stages of what may be a distmct species or 



Figure nz.-Opolina (?) from tadpoles of Rana damilans, X 673. 



160877—40- 



