THE OPALINID CILIATE INFUSORIANS. 421 



No 22802, 48 mm. loug; Lake Drummond, Virgiuia ; June 6, 1S9G ; \V. I'al- 

 mer ; no Opalinids. 

 Rappia vermiculata Peters. No. 57522, 25 mm. long; Uganda, Britisli East 



Africa; Julius Hurter, sr. ; no Opalinid.s. 

 • Rhyncophonis maculatus" (probably Polypedates Icucomystax) from I'er- 

 adeniya, Ceylon. Dobell reports Opalina virgnla. 



We have referred incidentally to the susceptibility of different 

 families of Anura to infection by different groups of Opalinidae. 

 There is no sharply defined specificity of infection, though there is 

 clear evidence of a broader grouping of hosts and parasites. 



The Discoglossidae contain Protoopalinae of the five species 

 caudata, intestinalis, orientalis, and macrocaudata; and one species, 

 Discoglossus pictus is known to contain a Cepedea. This family, 

 then, harbors the more primitive of the binucleated and of the multi- 

 nucleated Opalinidae. There is also a single report of Opalina 

 ranani/m in Borribina bomhina. The Discoglossidae have never come 

 into contact with Zelleriella. 



The Pelobatidae harbor a wider range of Opalinid parasites. The 

 European Pelohates fuscus contains Protoopalina pelobatidis, a spe- 

 cies of the archaic intestinalis group, and the Javan Megalophrya 

 montana bears a somewhat similar species, Protoopalina inontana. 

 The different species of Scaphiopus^ all American, are known to 

 bear nine species of Opalinids, three of these being Protoopalinae 

 {JiaTnmondii^ mesdcaTia^ scaphiopodos) all with midmitotic nuclei; 

 two being Zelleriellae {couchii, scaphiopodos) ; one being a Cepedea 

 {floridensis) . and three being members of the group of narrow species 

 of the genus Opalina,, all genera of the Opalinidae thus being known 

 from the Pelobatidae. Only the Opallnae latac arc unreported. It 

 seems that the Pelobatids are hospitable to any of the groups of 

 Opalinids, and possibly the only reason we know no broad Opalinas 

 from these hosts is because there are so few records of examination 

 of Pelobatids from the palaearctic habitat of the broad Opalinas. 

 Not only does the family Pelobatidae harbor all genera of Opali- 

 nids ; the same is true of the genus Scaphiopus. 



The Bufonidae, a wide-spread family, contain all genera of Opa- 

 linidae and both the nanow and the broad species of the genus 

 Opalina. They apparently collect whatever sorts of Opalinid are 

 present in their habitat. 



The Hylidae, a family found in tropical America and Australia, 

 some of whose members have spread to North America and through 

 North America to the northern parts of the Eastern Hemisphere, 

 show representatives of all genera of Opalinidae, but lack broad 

 species of the genus Opalina. Their Protoopalinas are all of the less 

 modified species and are reported only from Australia. Their 

 Zelleriellas are from Hvlas from Paraguay, Venezuela, and the West 



