Since the time of Linnaeus it has been the practice of naturalists to designate all species by double designations, the first part of the title indicating the genus to which the animal belongs, whilst the second is the proper or specific title. Thus the Dog is known by the "binomial" designation of Canis familiaris. The "genus" Cams contains other species besides the Dog - such as the Wolf and Jackal - but the name familiaris indicates that this title belongs to the Dog and not to either of the latter. The genus Canis, again, belongs to the "family" Canidae, including other genera, such as the Foxes (Vulpes). The family Canidae, further, is one of a number of families, such as the Cats (Felidoe), the Bears (Ursidoe), the Hyaenas (Hycenidoe), etc, which collectively constitute the ' order "of the Carnivora or Beasts of Prey. The Carnivora, again, constitute one of many orders of quadrupeds, which are distinguished by suckling their young and by other common characters, and which collectively constitute the "class" Mammalia. Finally, the Mammalia are united with the classes of the Birds, Reptiles, Amphibians, and Fishes to constitute the great primary division or "sub-kingdom "of Vertebrata or "Vertebrate animals;" since all these classes agree with one another in certain fundamental points of structure.

Condensing the above, the name of Cams familiaris, as applied to the Dog, implies a large amount of information as to the precise zoological position and affinities of the animal. Its title, namely, if expressed in full, would indicate its systematic place to be as follows:

Sub-kingdom, Vertebrata.

Class, Mammalia. Order, Carnivora. Family, Canidoe. Genus, Canis. Species, Canis familiaris.