90 CATALOGUE OF THE RECENT FORAHINTFERA OF 



the medium of another language their existence was commonly 

 entirely ignored. Hence we find that many of the commoner 

 types of the Foraniinifera have received fresh names from almost 

 every successive writer who has noticed them. Add to this the 

 fact only recently fully appreciated, that a much wider range of 

 variation must be allowed in grouping these protean animals than 

 it is the custom to admit in the more highly organized classes 

 with which the Foraminifera were for long associated, and we 

 have elements of confusion which could not well be surpassed. 



Owing partially to the low organization of the Protozoa, and 

 partly to the unusual facilities which they offer for comparative 

 study, we probably possess the elements of a fuller knowledge of 

 their natural relationships than has yet been attained in respect 

 to animals of more complex structure. Thus the relationship of 

 individuals to a sub-varietal form, of several such sub-varieties 

 to a variety of greater permanence, of many varieties to a sub- 

 type, and of a group of subtypes to one central type may often be 

 traced. Yet none of these groups would exactly correspond to 

 what would be regarded as a genus or a species in the true Lin- 

 nean sense. Probably what is included in the term "type" would 

 most nearly represent a " species," but it is doubtful whether, if 

 it were used in an absolute sense, representing a group which does 

 not inosculate with any other parallel series, the list would have 

 to be still further reduced. The "types," nevertheless, embrace 

 large numbers of so-called species, and often even many quasi- 

 genera ; but, though it is easy to pick out and name the promi- 

 nent varietal forms, there are no sharp lines of demarcation 

 between them, but the individuals constitute a continuous series 

 in which the degree of differentiation between the successive 

 specimens becomes less and less sensible as the number of con- 

 stituents is increased. 



That this tendency to variation exists amongst Protozoa lower 

 in organization than the Foraminifera, possibly to an even greater 

 extent, has been fully demonstrated by Dr. "VVallich in his recent 

 admirable papers in the Annals and Magazine of Natural His- 

 tory, and indeed is only what might have been expected. Thus 

 the naked Ehizopoda seem all referable to one primary type 



