428 BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



from some Asiatic species, since none of these Irogs in America have been 

 found to harbor Opalinids. It is of interest, in this connection, to note 

 that the southern bullfrog of America, Rana (/rylio, only preserved speci- 

 mens of which have been available for study, has not been found bearing 

 Opalinids. 



R. clainitans: Of 24 living specimens from North Carolina none bore Opalinids; 

 numerous living specimens from Ohio were found uninfected. In preserved 

 specimens of this frog no Opalinids have been found. It is evident that this 

 large, common American " green frog," like the still larger American bull- 

 frogs of both species, rarely, if ever, carries Opalinids. Tadpoles, probably of 

 this species, collected by Dr. Charles E. Simon, in Nova Scotia, bore Opalinae 

 of a species tentatively named 0. [hn-varum], but we have no data as to the 

 proportion of the larvae infected. 



R. draytonii: Of numerous living specimens from near San Francisco, Cali- 

 fornia, 1 held Zelleriella ranaxcna and 2 carried Opalina draytonii; 4 other 

 living specimens from south of San Francisco bore no Opalinids ; 22 living 

 specimens examined at Friday Harbor, Washington, bore no Opalinids, but 

 they had been over a month in captivity. It seems that this species of frog 

 is seldom infected. 



R. esculent a: Of 77 living specimens examined by Metcalf, 59 carried Cepedea 

 dimidiata; 2 or more bore both this species and its form zelleri; 16 bore no 

 Opalinids. In reexamining some of this Bavarian matei*ial I find more than 

 two, apparently six, specimens bore both forms of this Cepedea, the zelleri 

 foi'ms in four of the infections being not so large and stocky as in the two 

 previously recorded. Andre (1913) reports that from 82 per cent to 89.2 per 

 cent of frogs of this species from different localities in Switzerland are in- 

 fected with C. dimidiata. 



R. palustris: Of 3 living specimens from North Carolina, 1 bore abundant 

 Opalina obtrigonoidea and 2 were uninfected ; of 8 living specimens from 

 Massachusetts, 4 bore 0. obtrigonoidea and 4 were uninfected ; of many speci- 

 ment from Ohio, the author would say from memory that about one-third were 

 infected with the same species of Opalina. 



R. pipiens: Numerous living specimens from North Carolina, Ohio, and Illinois 

 yielded Opalina, obtrigonoidea, but the notebook containing the records is mis- 

 laid and from memory I can not say as to the percentage infected. Infections 

 were not at all rare. 



R. pipi^ens splienocephala: Of 8 living specimens from North Carolina 2 bore 

 Opalina carolinensis. 



R. sylvatica: Of 5 living specimens from Ohio, 3 carried Opalina virguloidea; 

 of numerous living specimens from North Carolina, about two-thirds bore the 

 same Opalina. 



R. temporaria: Of 15 living specimens examined by Metcalf, 10 bore Opalinu 

 ranarum and 5 had no Opalinids ; of 233 specimens examined by Andre (1913) 

 173 bore O. ranarum. 



These data are inadequate for any satisfactory answer to the ques- 

 tion of the frequency of infection of the Anura by Opalinids. It 

 seems clear that species differ in the proportion which are infected. 

 Quite probably the American Rana catesheiona., R. gmjlio., and R. 

 clamitans, at least when adnlt, are never infected. Tadpoles, prob- 

 ably of R. alamitans, are sometimes infected. The European Bom- 

 hikuc pachypa, on the other hand, is usually infected. The adults 



