1912'] Zoology in America 61 



naeus had in mind. They are only groups of individuals sub- 

 ject to the transforming influence of many factors. Ideally 

 the systematist when he lists his form should not only be able 

 to pick out its characteristic points, but through comparison of 

 many live individuals from different localities and through 

 experiment he should know whether such characteristics are 

 produced and maintained through the continuous action of 

 food, climate, or other environmental influences; or whether 

 they are ingrained in the constitution of the race, viz., hered- 

 itary, and so in some degree independent of the environment. 

 Should the characteristics prove hereditary, the relation of the 

 new form to other closely similar "kinds" should be determined, 

 before the form in question is listed as species, subspecies, mu- 

 tation, or what not. If the systematist should carry out this 

 ambitious program for all the kinds of animals he encounters, 

 his task would indeed be stupendous. For the most part he 

 must be content with listing his kinds in such wise as to make 

 it a known and accessible fact that a form of definite anatomical 

 peculiarities occurs in such and such a region. This done, he 

 has advanced science measurably, and may leave it to others, or 

 to himself in another capacity, to select from the vast mass of 

 species certain ones for intensive study of a comparative and 

 experimental character. 



Many of the ablest and most highly praised pieces of zoolog- 

 ical work emanating from America have been memoirs in sys- 

 tematic zoology. But it should be added that such memoirs 

 show us that great success in classification requires a wide and 

 deep knowledge of the group to be handled. The classifier 

 should, above all, be familiar with the comparative anatomy 

 and embryology of the group, and with the periodic or other 

 modifications of structure incidental to function, habit, or 

 nature of the home. And this means that he must be familiar 

 with his forms as living animals, and that the size of the group 

 be not too large. As representative classics in American system- 

 atic zoology I may pick out for mention Audubon's Birds (1827- 

 38), Holbrook's Herpetology (1836-40), Dana's Crustacea of the 

 Wilkes Exploring Expedition (1852), Louis Agassiz's Memoirs 



