CLASSIFICATION 7 



should be avoided where possible, varieties being a pre- 

 ferable term. It must always be remembered that indi- 

 vidual variations occur even in the offspring of a single 

 pair, and still more frequently in the progeny of a group 

 of animals belonging to the species. Such individual 

 variation does not constitute specific difference, however 

 great it may be ; and the formation of a new species, and 

 still more of a new genus, based on the examination of 

 a single specimen, is to be deprecated. 



Nomenclature. Even more than with Protozoa, difficult 

 questions as regards nomenclature arise. There is at 

 present much confusion. In the past, independent 

 workers have severally described under different names 

 the same parasite. Others, finding the number of para- 

 sites described under one generic heading too large, have 

 grouped them into separated genera or sub-genera and 

 done this in different ways. The names originally given 

 for a species or genus often have been ignored, and other,, 

 possibly more descriptive, names have been substituted 

 for them. The result of such changes is a wild con- 

 fusion. Zoologists, realizing this condition, have attempted 

 to rectify it, and it is now decided that the original 

 name is the name to retain : that if a generic name is 

 given that name must be the generic name of the species 

 first described of that series, and that if it is deemed 

 necessary to form other genera, though the generic name 

 is to be altered the specific name remains good. 



It is to be hoped that these efforts will be crowned 

 with success, but at present there is still confusion, as 

 according to these rules old names that had become 

 obsolete have had to be revived. A close study of older 

 literature, sometimes a hundred years old, has resulted in 

 displacing familiar names by forgotten ones. It is much 

 to be feared that unless a time limit be made and a definite 

 system of registration adopted further changes will ensue 

 in the nomenclature when the mass of published, but 

 not necessarily printed, literature now hidden in the 

 archives of universities, learned societies and government 



