THE OPALINID CILIATE INFUSORIANS. 271 



shows US among the Flagelhita a highly ciliate form like the Opa- 

 linidae and the lowlier of the Euciliata. It seems still more prob- 

 able that the Euciliata arose from ancestors which, like Frotoopalina 

 to-day, had become disturbed in their relations of mitosis and fission, 

 and that they passed through a similar pseudobinucleated condition 

 to a condition of true binucleation and finally reached their present 

 structure with nuclei of two sorts, one hypertrophied for metabolism, 

 the other inactive except during the sexual period, when it functions 

 in the phenomena upon which inheritance is dependent. The rela- 

 tionship with the Euciliata here suggested may be expressed by the 

 following classification : 



Ciliata 



I. Protociliata. 



Opalinidae. 



Protoofolininae. 

 Protoopalina. 

 ZelJeriella. 

 Opalininae. 

 Cepedea. 

 Opalina. 



Opalhiae latae {Orieiitales). 

 OpaJinac august ae {0 ccidentales) . 



II. Euciliata. 



7. THE HOSTS AND THE GEOGRAPHICAL DISTRIBUTION OF THE 

 SEVERAL SPECIES AND GROUPS OF OPALINIDAE, WITH A DIS- 

 CUSSION OF THE DISTRIBUTION OF THE FAMILIES AND SUB- 

 FAMILIES OF THE ANURA. 



In section 3, in connection with each species of Opalinid de- 

 scribed, there are given, so far as known, the name of the host, the 

 locality and date of collection, and the name of the collector. Here 

 will be given a condensed table showing the species of Opalinid, the 

 host, the family or subfamily of the host, the known geographical 

 occurrence of the Opalinid, the known geographical occurrence of 

 the host species, the known geographical occurrence of the genus of 

 the host, and, finally, in a separate list, the known geographical dis- 

 tribution of the families and subfamilies of the Anura. If we had ex- 

 tensive knowledge of fossil Anura, reference to their paleogeographic 

 distribution would be given under each genus. As it is, the only 

 reference is under the several families and subfamilies. This will 

 give us a conspectus of the hosts and geographical distribution of 

 the family Opalinidae, and of its genera and species. There have 

 been reported heretofore 55 infections by Opalinids, including sev- 

 eral doubtful records and counting the infection of each species and 

 subspecies of host by each species and subspecies of parasite as one 

 unit. This paper adds 173 new infection records, making 228 in all. 



