Every North American bird has a common or vernacular name author- 

 ized by usage and recognized by the leading ornithologists and there is 

 seldom necessity for using the scientific nomenclature. However, it is well 

 for all who are interested in birds to familiarize themselves with as many of 

 the scientific names as possible, as they are not only necessary in more 

 advanced work, but they are of practical use in grasping the general 

 relationships between various species. 



The present binomial system of nomenclature was introduced by 

 Linnaeus, the great Swedish botanist, and embodied in his "Systema 

 Naturae," tenth edition, 1758, which is the authority accepted by 

 American ornithologists. In this system each species is given a double 

 name, the first term being that of the genus to which it belongs, the 

 second that of the species. Generic names are not duplicated within 

 the sphere of zoology nor are specific names within the genus. Thus, 

 the American Robin is Planesticus migratorius; that is, that species of 

 the genus Planesticus which is named migratorius. Other species of 

 Planesticus have other specific names. 



The three objects of scientific nomenclature are exactitude, univer- 

 sality, and permanence. To this end the naming of zoological material 

 is subject to strict laws whose principles are universally accepted and 

 applied according to strict codes. Under these laws the scientific name of 

 a species is not a matter of personal preference, but is fixed, so chat few or 

 none can dispute it, and no changes can be made in scientific nomenclature 

 except such as are necessary to correct current mistakes in the application 

 of the laws of the code. With increased knowledge it has become neces- 

 sary to depart slightly in letter, though not in spirit, from the strict 

 binomial system of Linnaeus, and by adding a third term as name of the 

 subspecies to make it a trinomial one. Wherever a three-term name 

 is used, it is that of a subspecies of the original binomial form. The first 

 specimen described, or the first specimen to which a name has been 

 attached, is regarded as the so-called "Type" form. Therefore, in dividing 

 a species into subspecies the form which was first named as a species 

 is naturally given precedence and its subspecific name is formed by a 

 repetition of its specific name. Thus the American Robin that was 

 first described and specifically named by Linnaeus in 1766 as migratorius 

 when mentioned subspecifically in distinction from the Southern Robin or 

 the Western one becomes Planesticus migratorius migratorius. The Western 

 Robin, first separated from it by Ridgway in 1877, was named by him as 

 Planesticus migratorius propinquus, and the Southern Robin by Batchelder 

 in 1900, is Planesticus migratorius achrusterus. In practice, where the 

 generic or specific names are evident from the context, it is customary 

 to indicate them by initial, as P. migratorius, or P. m. migratorius. 



Subspecific varieties are divisions of the species and, except in special 

 lines of work, or where special exactitude is necessary, are of minor import- 

 ance. As these subspecies are also often based upon points of difference 

 perceptible to only the most experienced observers, they are mainly outside 

 the sphere of interest of the average amateur observer. 



