42 ESSAY ON CLASSIFICATION. Part I. 



acter of their representatives in other parts of the world ; unless it could be shown 

 that such agents have the power of discrimmation, and may j'i'otluce, under the same 

 conditions, beings which agree and others which do not agree with those of different 

 continents ; not to speak again of the simultaneous occurrence in that same continent 

 of other heterogeneous types of Mammalia, Bats and Rodents, which occur there 

 as well as everywhere else in other continents. Nor is New Holland the only part 

 of the world which noin-ishes animals highly diversified among themselves, and yet 

 jiresenting common characters strikingly different from those of the other members 

 of their tj^e, circumscribed within definite geographical areas. Almost every part 

 of the globe exliibits some such group either of animals or of plants, and every 

 class of organized beings contains some native natural group, more or less extensive, 

 more or less prominent, which is circumscribed within peculiar geographical limits. 

 Among Mammalia we might quote further the Quadrumana, the representatives of 

 which, though greatly diversified in the Old as well as in the New World, differ and 

 agree respectively in many important points of their structure; also the Edentata of 

 South America. 



Among birds, the Humming Birds, which constitute a very natural, beautiful, 

 and numerous family, all of which are nevertheless confined to America only, as the 

 Pheasants are to the Old World.^ Among Reptiles, the Crocodiles of the Old World 

 compared to those of America. Among fishes, the family of Labyrinthici, which is 

 confined to the Indian and Pacific Oceans, that of Goniodonts, which is limited to the 

 fresh waters of South America, as that of Cestraciontes to the Pacific. The compar- 

 ative anatomy of Insects is not sufficiently for advanced to furnish striking examples 

 of this kind ; among Insects, however, remarkable for their foi'm, which are limited 

 to particular regions, may be quoted the genus Mormolyce of Java, the Pneumora 

 of the Cape of Good Hope, the Belostoma of North America, the Fulgora of China, 

 etc. The geographical distribution of Crustacea has been treated in such a masterly 

 manner by Dana, in his great work upon the Crustacea of the United States Explor- 

 ing Expedition, Vol. XIII., p. 1451, that I can only refer to it for numerous examples 

 of localized types of this class, and also as a model how to deal with such subjects. 

 Among Worms, the Peripates of Guiana deserves to be mentioned. Among Cepha- 

 lopods, the Nautilus in Amboyna. Among Gastero]3ods, the genus lo in the western 

 waters of the United States. Among Acephala, the Trigonia in New Holland, certain 

 Naiades in the United States, the Aetheria in the Nile. Among Echinoderms, the 

 Pentacrinus in the West Indies, the Culcita in Zanzibar, the Amblj-pneustes in the 

 Pacific, the Temnopleurus in the Indian Ocean, the Dendraster on the western coast 



^ What are called Pheasants in America <lo not ants. Tlie American, so-called, Pheasants are gen- 

 even belong to the same family as tlie eastern Pheas- uine Grouses. 



