20 SCIENTIFIC NOMENCLATURE 



sometimes many, as in the case of the first five geese, B. canadensis, in 

 which case a subspecific or third name must be added as the name of 

 each of the slightly different geographic races. 



(In the case of the American Brant, Branta bernicla hrota, the use 

 of the third term, hrota, implies the existence of more than one sub- 

 species in the species B. bernicla; and this is the case, but the others are 

 not listed here as they are exclusively Old World varieties and do not 

 come within the scope of this work.) 



The foregoing explanation should be re-read carefully to make cer- 

 tain that it is fully understood. The reader is then advised to check over 

 carefully the other subfamilies and work out for himself how they, 

 in turn, are subdivided into genera, species and subspecies. 



The words Family, Subfamily, Genus, Species, and Subspecies, 

 which have been used above, will now be defined briefly: 



FAMILY. A group of birds, having enough mutual resemblance to 

 be classed together and apart from all other birds. All the Swans, Geese, 

 Ducks and Mergansers, for example, belong to the same Family, Ana- 

 tidae. 



SUBFAMILY. A group of birds within a Family, having enough 

 mutual resemblance to be classed together and apart from those of the 

 other Subfamilies. For example, (a) the Swans, Cygninae, (b) the Geese, 

 Anserinae, (c) the Diving Ducks, Nyrocinae; etc. 



GENUS (plural, genera). A group of birds within a Subfamily, 

 consisting of a number of species which are closely related. The genus 

 Nyroca, for example, in the Subfamily of Diving Ducks, which comprises 

 five closely related species. Note: A Genus may also consist of but a 

 single member; the Genus Philacte, for example, of the Subfamily of 

 Geese. 



SPECIES. A group of individuals, within a Genus, having com- 

 mon characteristics. The species canadensis, for example, within the 

 Genus Branta, in the Subfamily Geese. Note: A species may also consist 

 of but a single member; for example the species leucopsis (Barnacle 

 Goose), within the genus Branta, of the Subfamily of Geese. 



SUBSPECIES. A division of a species: a distinguishable form being 

 part of a species; also called a "variety" or a "race." A subspecies is 

 divisible only into individuals; the subspecies borealis, for example, 

 of the species S. mollissima, the Northern Eider. 



EXAMPLES, (a) The Cackling Goose is the subspecies minima, of 

 the species canadensis, of the genus Branta, of the subfamily Anserinae, 

 of the family Anatidae. (b) The Ruddy Duck is the subspecies rubida, 

 of the species jamaicensis, of the genus Erismatura, of the subfamily 

 Erismaturinae, of the family Anatidae. (The other subspecies of the 

 species jamaicensis do not visit North America.) (c) The Canvas-back is 

 the species valisineria, of the genus Nyroca, of the subfamily Nyrocinae, 

 of the family Anatidae. 



It will have been noticed that the name of a Genus is referred to as 



