THE OPALINID CILIATE INFUSORIANS. 329 



of the host, even in spite of its identification as Bufo riielanostictus. 

 One wonders if there could have been any confusion of labels, or 

 if the host in question might have become infected from some South 

 American Anuran with which it may have been kept and which it 

 may have eaten. Of course the record must stand as given, but 

 until confirmed by further study of the parasites of Bufo vielano- 

 stictus, one can not base conclusions as to geographical distribution 

 upon this isolated report. I have opened 39 specimens of this toad 

 without finding ZelJeriella. 



ZellerieUa is not only a western hemisphere genus; it is chiefly 

 South American and Central American. Two species have pushed 

 north to California, Z. ranaxena from Rana draytonii which occurs 

 also in Mexican California, and a form from Bufo pimctatics, 

 which may not be specifically distinct. Five forms have moved 

 up into northern Mexico and southwestern United States: Z. 

 hirsuta, in Bufo cognatus; Z. intermedia, in Bufo intermed'ius ; 

 Z. intermedia cimeata, in Bufo valliceps; Z. [of Bufo woodhousi]^ 

 in Bufo woodhousi; Z. couchil, in Scaphiopus couchii. Another 

 species, also in a Scaphiopus (solitarius) , Z. scaphiopodos, has passed 

 eastward along the north coast of the Gulf of Mexico to the At- 

 lantic Seaboard. CTie species (perhaps also a second, Z. sp. ?) is 

 known from the West Indies and another occurs in the Bahamas. 

 No account need be taken of the species in Bufo marinus, 

 recently introduced into the West Indies and Bermuda. The 

 Zelleriellas are the characteristic Opalinids of tropical and south- 

 temperate America. It is. then, only natural that they should 

 be abundant in two of the families abundant in this region, 

 the Leptodactylidae and the Bufonidae. Similarly their al- 

 most complete absence from the genus Bana corresponds to the fact 

 that only one Rana is known from South America. It is remarkable 

 that only three species of the large family Hylidae are known to 

 harbor ZellerieUa, though the home of the Hylidae is the great forest 

 region of tropical America ; and of the three Hylas which we know 

 bear Zellenella only two belong in continental America, one being 

 Bahaman. 



The geographical distribution of ZellerieUa outside of America is 

 significant. ZellerieUa macronucleata is said to occur in Bufo 

 melanostictus from "Asia," but this seems so anomalous that we must 

 leave it out of account until confirmed. Species of ZellerieUa almost 

 identical with this form are found in American toads. ZellerieUa 

 hinucleata occurs in two Australian Leptodactylids, while among the 

 American Leptodactylids occur Zelleriellas so similar that their spe- 

 cific distinctness from the Australian form is uncertain. Some stu- 

 dents of geographical distribution, Gadow for example, endeavor to 

 83103—23 22 



