hours, and which in the winter dark of northern latitudes must be lighted up once or twice in the night to have the opportunity of feeding. Knowledge of the habits of animals and experience are the best guides to the nature of food to be supplied, but the keepers should be required to observe the droppings of their charges and to judge from these of the extent to which any particular substances are being digested. The feeding of carnivores is on the whole the most easy; the chief pitfall being the extreme liability of all except the larger forms to fatal digestive disturbances from food that is not quite fresh. The more powerful creatures in a state of nature are accustomed to kill a prey too large to be devoured at once, and to return to it again and again, long after it has become putrid; the smaller forms, for the most part, devour nothing but small creatures immediately after they have been captured and killed, and consequently in an absolutely fresh condition. The chief danger with herbivorous and frugivorous creatures is that their constitutions are not adapted to the richness of cultivated fruits and cereals, and, in captivity, they may suffer mechanically from the want of bulk in their food supply, or if they eat a quantity sufficient in bulk, it contains an excess of nutritive material. A minor problem in menageries is injudicious feeding by visitors. Many authorities attempt to restrain visitors from feeding the animals in their charge, but such a restriction, even if practicable, is not all gain, for animals in captivity are less inclined to mope, and are more intelligent and tamer, if they become accustomed to regard visitors as pleasant sources of tit-bits.
Literature.—S. S. Flower, Notes on Zoological Collections visited in Europe in 1907 (Public Works Dept., Cairo); Reference List of the Zoological Gardens of the World (1910); C. V. A. Peel, The Zoological Gardens of Europe (London, 1903); "Bulletins of the Zoological Society of New York" (with many photographs and plans of buildings and enclosures); Annual Reports of the Smithsonian Institution, Washington; G. Loisel, Rapport sur une mission scientifique dans les jardins et établissements zoologiques publics et privés du Royaume-Uni, de la Belgique et des Pays-Bas, et des États-Unis et du Canada, et conclusions générales (Paris, Imprimerie Nationale, 1907, 1908; with many photographs and plans). (P. C. M.)
ZOOLOGICAL NOMENCLATURE, the system by which it is attempted to designate, exactly and conveniently, the animals which exist now or are known to have existed. It is, in fact, the grammar of classification, and has the advantage that it is international. The popular names of animals differ from country. to country, but even amongst civilized peoples, and still more amongst uneducated persons and the lower races, the animals denoted by popular names are a very small part of existing forms, whilst the connotation of the names is vague and varying. Linnaeus was the first to adopt a precise system, which he explained and applied in 1751 in his Philosophia botanica, and later extended to animals in the tenth edition of his Systema naturae (1758). The foundation of the system was the application of a binomial nomenclature to species (see Species). Each species was to be designated by two latinized names, the first being that of the genus to which it belonged, and the second the appellation peculiar to the species. There are many different cat-like animals, such as the common cat, lion, tiger and so forth, more obviously related to one another than they are to dog-like or hyaena-like carnivores. The assemblage of cats constitute the genus Felis, the wild cat being one species, Felis catus, the lion another, Felis leo, the tiger yet another, Felis tigris, and so forth. The various genera were grouped into families, the family taking its designation from the leading genus, as, for instance, the family Felidae for the cats. Families were associated in orders, as the Cats, Dogs, Bears, &c., in the order Carnivora, and the orders in Classes. There is still little uniformity in the designation of the assemblages higher than families, and less agreement as to the degree or measure of separation to be indicated by the use of the designations employed. For the system adopted in the present work, see Zoology.
Linnaeus named very many species and genera, but the number known continues to increase at a prodigious rate, while precision of description has far surpassed his conceptions, with the result that his rules have long ceased to meet the needs of modern science. In 1842 the English ornithologist, H. E. Strickland, assisted by a committee of which Charles Darwin was a member, elaborated rules which became known as the Strickland Code, and were ado p ted in 1845 by the American Society of Geologists and Naturalists, and in 1846 by the British Association for the Advancement of Science. In 1881, the International Congress of Geology, meeting at Bologna, constructed a code differing in many respects from that of Strickland and specially applicable to fossil forms. In 1881 the Zoological Society of France agreed on new rules, based on those of Strickland, but formulated by a committee of which Maurice Chaper and R. Blanchard were leading members. In 1885 the American Ornithologists' Union, urged by the needs of the great advance in ornithology in America, adopted rules which were still further modified from the Strickland Code. In 1894 the Zoological Society of Germany framed another set of rules drawn up by J. V. Carus, L. Doderlein and K. Mobius. In 1896 the English entomologist Lord Walsingham devised another modification of the Strickland Code, which became known as the Merton Rules, followed by many entomologists. The existence of so many conflicting authorities caused much confusion and an impractical condition of anarchy in which many distinguished and active systematists elaborated practices individual to themselves. When the International Congress of Zoology held its first meeting in Paris in 1889, one of the chief objects submitted to it was the necessity of framing rules which should be uniform in their application to the whole animal kingdom and which might receive international sanction. The discussion was carried over to the second meeting of the Congress, held at Moscow in 1892, when a code prepared by R. Blanchard was accepted. Further modifications were made, partly to reconcile it with the German Code, and a permanent commission was appointed to consider fresh points that might arise. In 1905 there was published, with the sanction of the Congress, in French, English and German (International Rules of Zoological Nomenclature, Paris, 1905, F. R. de Rudeval) a set of rules finally codified by MM. R. Blanchard, von Maehrenthal and C. W. Stiles, which appears to be a close approach to an international system applicable to every group in the animal kingdom. At subsequent meetings of the Congress minor alterations have been proposed and no doubt will continue to be proposed and occasionally adopted, but with one important exception, to be referred to later, fundamental lines of agreement appear to have been reached, and many of the most active workers have accepted the international code as binding. It is possible here to give only a short summary of the more important rules.
The goal to be reached is that the connotation and denotation of every zoological designation should be definite. One name is to be used for each sub-genus or higher group, two names for each species (following the invention of Linnaeus) and three names for each sub-species (a refinement not necessary in the time of Linnaeus). The scientific names must be Latin or Latinized forms. The name of a family is to be formed by adding the ending idae, the name of the sub-family by adding the ending inae to the root of the name of the genus from which it is derived, as Felidae and Felinae from Felis. When a generic name is changed there must be a corresponding change in the name of the family or sub-family derived from it. A generic name must consist of a single word, written with a capital initial letter, and treated as a substantive in the nominative singular. When a genus is divided into subgenera the name of the typical sub-genus must be the same as the name of the genus, and when it is desired to cite the name of a sub-genus this name must be placed in parentheses between the generic and the specific names, as, for instance, Vanessa (Vanessa) cardui and Vanessa (myrameis) cardui respectively, for the typical sub-genus and another sub-genus of the genus Vanessa. Specific names are adjectives, substantives in apposition with the generic name or substantives in the genitive; they are written with a small initial letter except when they are substantives derived from the name of a person, but even in the latter case it is permitted and is becoming usual to employ the small initial letter, as Gazella cuvieri. If it be desired to cite the sub-specific name, such name is written immediately following the specific name without the interposition of any mark of punctuation, as Rana esculents marmorata. The author of a scientific name is that person who first publishes the name in association with a clear indication of what the name denotes, and if it be desired to cite the author's name, it should follow the specific name in a different type but without the interposition of any mark of punctuation, e.g. Felis catus Linnaeus. Names are merely designations, or recognition marks, and not descriptions, and hence a name is not to be rejected or changed if it is otherwise valid, because it gives a wrong description; there is no more reason why Felis rufus should be a ruddy cat than John Black a person of swarthy complexion; nor is a name to be rejected
