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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 87 



Adult R. clamitans have no opalinids.^ The tadpoles live for more 

 than a single year in the pools. The opalinids in last year's tadpoles 

 divide and become small, encyst and pass out of the rectum into the 

 water, and serve as infection cysts for young tadpoles of the new crop 

 (Brumpt, 1915). The infection is thus from tadpole to tadpole, the 

 narrow Opalina stage not being foimd in any adults, for they are not 



Figure 112.- 



-Opalina lariarumMetcaMiioin Woods Hole, Mass. (a), and Philadelphia, Pa. (6), X 482; from 

 a slide prepared by Prof. D. H. Wenrieh. 



infected, and being foimd only occasionally in the oldest tadpoles 

 that have almost completed metamorphosis. 



Similarly, the adult R. catesbeiana is miinfected, although its larvae 

 are well infected. The large tree-frog Hyla versicolor shows a more 

 delayed suppression of its Opalinae. I have never found a tadpole 

 of this species iminfected and I have never found a full-grown adult 

 infected, but small tree-frogs, less than half grown but completely 

 past metamorphosis, show abundant narrow Opalinas of a species that 

 I have described as 0. hylaxena. 



In tadpoles of R. clamitans, as I showed in 1923a, there are found 

 many broad, flat Opalinas, generally with an abrupt, curved point 



« There are a few reports of Opalina in adult Rana clamitans and R. catesbeiana. Some of these reports 

 are of captive frogs fed on tadpoles; others are of artificial infections; a few others are of infections of adults in 

 nature, but the infections may have been due to devouring tadpoles. 



