TEINOMIAL NOMENCLATURE IN ZOOLOGY. 243 



sign has been entirely done away with by the leading ornithologists 

 of this country. The latest lists of our birds discard it altogether, 

 and present a decided and radical innovation upon any binomial 

 nomenclature, by employing the three terms consecutively with- 

 out the intervention of any sign whatever, as, Turdus migratorius 

 propinquics. This method, moveover, as used by competent 

 ornithologists, has a meaning and significance of its OAvn. It is 

 not simply a question of recognizing any variation, any 

 abnormality, any sport, as I may call it, any variety in the old 

 sense of the word ; for we proceed upon a perfectly definite, well- 

 understood and recognized principle of variation, viz., variation 

 according to conditions of physical environment, using this term 

 in the largest sense, to cover all those exterior influences which 

 exert a modifying influence upon animal organisms. 



From our study of North American birds, which are perhaps 

 better known than the same number of birds of any other portion 

 of the world, we have so exactly traced their geographical 

 variations that we are enabled in some cases to positively foretell 

 what will be the characteristics of a given bird in a given 

 geographical area. In one case at least, within my knowledge, 

 before any specimens were received, a given set of sub-specific 

 characters were hypothetically assigned to a bird {Junco connecteus 

 Coues) from a particular region ; and, upon receipt of specimens, 

 the hypothetical characters of the presumed sub-species were 

 confirmed. 



Here is the definite principle and rule of action in the appli- 

 cation of such trinomials. That the third term of the technical 

 name is given to climatic or geographical races varying according 

 to known conditions, as latitude, elevation, temperature, moisture 

 and conditions of all sorts. The practice, therefore, has a logical 

 basis, a consistent possibility of strict scientific application. It 

 appears to me to be a simple, natural and easy way of disposing 

 of a large number of intermediate forms which have not become 

 specifically distinct from their respective nearest allies. It is 

 quite true that the recognition of this result of climatic conditions 

 is largely a matter of tact and judgment, and that it is not always 

 possible to say whether a given organism is or is not " specifically " 

 distinct from another. 



There is in this use of trinomials, as you perceive, a principle 

 of practical application entirely different from the more 



