ZOOLOGISTS and botanists universally adopt what is termed the binomial system of nomenclature invented by Linnaeus. The essential principle of this system is, that every species of animal or plant is to have a name made up of two words, the second word—which is called the specific or trivial name, having exclusive reference to the species itself, the first word—which is called the generic name, indicating the genus, or small natural group, which comprises the species in question along with others. Thus the cat, the tiger, and the lion, belonging to one genus or small natural group of closely-allied animals, are called respectively, Felis cattus, Felis tigris, and Felis leo, The name of each species, therefore, shows us what group it belongs to, and thus gives us a clue to its affinities; and the system, of nomenclature is to this extent classificatory. But, as the true natural grouping of species has not yet been agreed upon by naturalists, and genera have been in a state of incessant change from the time of Linnaeus to the present hour (or for about a century), the names of an immense number of species have been repeatedly altered; and one of the first requisites of a good system of nomenclature—that the same object shall always be known by the same name—has been lost, in the attempt to make the name a guide to classification, while the classification itself has ever been fluctuating and still remains unsettled. As an example let us take the Snowy Owl. This has been placed by different ornithological authors in the genera Bubo, Strix, Noctua, Nyctea, Syrinium, and Surnia; and at the same time, owing to carelessness or error, a number of different specific or trival names have also been used, such as scandiaca, artica, nivea, erminea, Candida, and nyctea; and the various combinations of these two sets of names have led to the use of about twenty distinct appellations for this single species of bird. This example is. by no means a very extreme one; and it represents what occurs over and over again, in varying degrees, in every department of zoology and botany. The Object and Method of Zoological Nomenclature. By David Sharp. (E. W. Janson and Williams and Norgate, 1873.) Pp.39.