exclusive of a few minor papers, are comprised in the "Fauna Suecica," the "Museum Adolphi Friderici," the "Museum Ludoviciæ Ulrica" and the several editions of his "Systema Naturæ." The first edition, appearing in 1735, was a folio of only 12 pages, consisting merely of a conspectus of his Systema in tabular form. The second edition, published in 1740, was an octavo of 40 pages, in which were added, for the animal kingdom, the characters of the groups. The sixth, published in 1748, was greatly enlarged, the zoological part alone consisting of 76 pages, illustrated with six plates, or one for each of his six classes of animals. The tenth, published in 1758, was in two octavo volumes, of which the zoology formed the first volume, consisting of 824 pages. The twelfth, and the last edition revised by the author, was issued in three volumes, the first of which, containing the zoology and comprising 1427 pages, appeared in 1766. Thus in thirty-three years this work grew from a brochure of 12 pages to a work of 2400 pages.

The first edition of the Systema was published when the author was only twenty-eight years old, during his sojourn in Holland. He had never previously been beyond the confines of southern Sweden, except on his journey to Lapland and Finland in 1732, and he had had access to no large collection of animals. Thus his resources for such an important undertaking were extremely limited, being restricted to his own considerable firsthand knowledge of the fauna of Sweden, to the few specimens of exotic animals he had been able to see in Lund, Upsala and Stockholm, and to the scanty literature of the subject there available. When the second edition appeared, in 1740, he had spent less than three years and a half in foreign countries, mainly in Holland with single brief visits to London and Paris; but his interests on these occasions were botanical and not zoological.

The sixth edition (the third revised by the author), published in 1748, was in effect a synopsis of the fauna of Sweden, filled in, as regards the fauna of the rest of the world, by compilations from his predecessors. Strange as it may seem, outside of the tropical genera Simia, Bradypus, Dasypus, Myrmecophaga and Manis, this edition enumerates only thirteen species of mammals not found in Sweden. Only 140 are recorded for his whole class Animalium quadrupedium, one-third of which are Scandinavian.

This analysis could be extended to other classes with practically similar results. The class Insecta, for example, includes only thirteen species that are not also recorded in the "Fauna Suecica," showing how limited was his knowledge of the world's fauna at 1748.

The tenth edition (the fourth revised by the author), published in 1758, is the epoch-making work in the history of zoology, as in this the binomial system of nomenclature for the whole animal kingdom is introduced for the

first time. The work is also greatly enlarged, and the classification greatly improved, especially that of the mammals, which class is now for the first time aptly designated Mammalia. The ordinal term Primates is substituted for Anthropomorpha of the sixth and previous edition, the sloths (genus Bradypus) are removed from it, the genus Lemur is added as a new genus, and the bats are transferred to it from the Feræ. A new order, Bruta, is made up of his former third order Agria (now suppressed) and of such other extremely heterogeneous elements as the elephant, the manatee, sloths, ant-eaters and the scaly ant-eaters. The order Feræ consists of six properly associated genera; the armadillos, insectivores and bats, formerly included in it, being removed elsewhere. His fourth order, Bestiæ, is a new group, composed of the pigs, armadillos, opossums and insectivores. The fifth order, Glires, is a natural group, except for the inclusion of the genus Rhinoceros, now most strangely placed with the squirrels and mice. His sixth order, Pecora, is retained as in the previous editions, and is also a natural group. The seventh, Belluæ, is a new ordinal group, consisting of the genera Equus and Hippopotamus, transferred from the here disrupted order Jumenta of previous editions. The Cete, now removed by him from the fishes, form his eighth and last order. This reconstruction of the ordinal groups is a great improvement: five new genera are added, two old ones eliminated, and the number of species is increased from 140 to 185. In some of the other classes there are similar radical changes, but there is not time to refer to them.

The twelfth, and the last edition revised by the author, published in 1766, shows many improvements over the tenth. It is greatly increased in bulk through the addition of many new genera and a large number of new species. The classification is also judiciously modified at many points. Taking again the class of mammals for illustration, the number of orders is reduced from eight to seven, through the suppression of the grossly unnatural order Bestiæ and the transference of its genera to other associations, with, however, the retrograde change of placing the insectivores and the genus Didelphis among the Feræ. The Glires is modified by the removal of the genus Rhinoceros to the order Belluæ and the addition to it of Noctilio, a genus of bats. The order Bruta is the same incongruous association of elephants, manatees, sloths and ant-eaters as in the tenth edition.

The orders of mammals as now left correspond in several instances very nearly with those of our modern systems, notably the Primates, Glires, Pecora and Cete. The Fera of the tenth edition corresponds to the modern Carnivora, but in the twelfth he made the mistake of putting back into it the marsupials and the insectivores. His order Belluæ being essentially the modern suborder Perissodactyla, his order Bruta is the only grossly incongruous association of types.

The only previous classification of mammals with which Linnæus's need to be compared is Ray's, published in 1693, whose system, taken as a whole, is far more artificial than Linnæus's. Naturally there are some striking coincidences of grouping, and in the characters employed by the two authors. As to the latter, Ray so well covered the field that there was little left for Linnæus to add, since during the interval between Ray and Linnæus not much was learned about the anatomy and relations of the ordinal groups of mammals. Doubtless Linnæus was influenced, in hist removal of the cetaceans from the fish to the mammal class, by the systems of his contemporaries, Klein (1751) and Brisson (1756), in which respect. only are their systems better or less artificial than his. Inasmuch, however, as Brisson divided mammals into eighteen orders instead of seven, he escaped some of the grotesque combinations made by Linnæus: on the other hand, he gave undue emphasis to relatively unimportant differences.

Linnæus's classification of birds is closely modeled upon that of Ray, and his departures from it are seldom improvements. His lack of knowledge of ornithology is strikingly apparent through his repeated association of very unlike species in the same genus, as where a penguin is combined with a tropic bird to form his genus Phaëthon, and another species of penguin with an albatross to form his genus Diomedea. In the tenth edition he recorded only about 550 species of birds; in the twelfth, this number was raised to nearly a thousand, mainly on the basis of Brisson's great work, which appeared in 1760. The greater part were based on the writings of previous authors; probably less than one-fourth of them being known to him from specimens.

His class Amphibia contained four orders, of which the fourth consisted of cartilaginous and other wholly unrelated fishes, and shows how slight was his acquaintance with the lower classes of vertebrates. His first order, Reptilia, includes such diverse animals as turtles, lizards, salamanders, frogs and toads. The snakes formed his second order, Serpentes.

His arrangement of the fishes was originally based on that of Artedi, whose "Ichthyologia" Linnæus published while sojourning in Holland, in 1738, after Artedi's untimely death by accidental drowning.

His class Insecta is nearly equivalent to the modern subphylum Arthropoda, as it includes the Arachnida and the Crustacea.

His class Vermes was the waste-basket of his system, including all the forms of animal life that were neither vertebrates nor insects, which he distributed into five orders, some of them as heterogeneous in character as the class itself. The second order, Mollusca, comprised all sorts of soft-bodied animals, mostly marine, as slugs, sea-anemones, ascidians, holothurians, cuttle-fishes, star-fishes, sea-urchins and jelly-fishes. The animals now commonly known as Mollusca formed his third order, Testacea.

It is not, however, just to judge Linnæus's work by the standards of to-day. The above comparison of the zoological part of the "Systema Nature" with our present knowledge of animals is not to be taken as a disparagement: we merely note the progress of zoology during the last century and a half of the world's history. Linnæus was a born systematist; his energy and industry were enormous; his isolation promoted independence and originality. He devised new classifications, and thoroughly systematized not only the knowledge of his predecessors, but the vast increment he himself added. He inspired his students with his own enthusiasm, taught them his own advanced methods, and influenced a goodly number of them to undertake natural history explorations in distant and zoölogically unknown parts of the world.

In special lines of research he was far behind several of his contemporaries, notably Brisson, in respect to both mammals and birds. But he nearly doubled the number of known forms of reptiles, amphibians and fishes, and increased many fold the number of species of Coelenterates, on the basis of wholly new material gathered through his own efforts.

Disgusted with the needlessly detailed accounts and repetitions that characterized the writings of most of his predecessors, he unfortunately adopted the extreme of condensation, thereby adding greatly to the difficulties of his successors in determining to just what forms the thousands of new names he introduced really belonged. Many of his species, based on the accounts given by previous authors, were also composite, often containing very diverse elements. But this detracts little from his credit. As one of his appreciative biographers has tersely put it, "He found biology a chaos; he left it a cosmos."

Linnæus's beneficent influence upon biology was hardly less as a nomenclator than as a taxonomist. He not only invented a descriptive terminology for animals and plants, but devised a system of nomenclature at once simple and efficient, and which for a hundred and fifty years has been accepted without essential modification.

Linnæus divided the three kingdoms of nature into classes, the classes into orders, the orders into genera, the genera into species, under which latter he sometimes recognized varieties. Of these groups, as he understood them, he gave clear definitions, but they were in most cases much more comprehensive than the limits now assigned to groups of corresponding rank. His genera correspond in some cases to groups now termed orders, and frequently to the modern idea of family; in some cases they contained species now placed in separate orders. Prior to Linnæus, these groups had less definite significance, and were often designated by a phrase instead of a single word. Species were indicated only by a cumbersome diagnosis

intended to express their chief distinctive characters. For this, Linnæus substituted a single word, an innovation the merits of which were at once almost universally recognized. But Linnæus reached this solution of a grave inconvenience somewhat slowly, and not till 1753 did he fully adopt the nomen triviale, when he introduced it into botany in his "Species Plantarum," which is taken by botanists as the point of departure for the binomial system. In the following year, 1754, he introduced it into zoölogy, using it throughout his "Museum Adolphi Friderici" for all the animals catalogued or described in this superb work; namely, 39 species of mammals, 23 of birds, 90 of reptiles and amphibians, 91 of fishes and 64 of invertebrates, or for an aggregate of 307 species of animals. Four years later, in the tenth or 1758 edition of his "Systema Naturæ," he adopted it for the whole animal kingdom, which date is now generally taken as the beginning of the binomial system for zoology. The importance and utility of this simple innovation in a matter of nomenclature are beyond estimate, and if Linnæus had done nothing else for the advancement of biology, he would be entitled to a conspicuous niche in the temple of fame and to the gratitude of all subsequent workers in this field. He for the first time gave technical standing to the systematic names, both generic and specific, of all the plants and animals known at the dates when he introduced the nomen triviale into the nomenclature of botany and zoology.

It is of interest in this connection to note the number of species of animals known to Linnæus at the date of publication of the last edition of the "Systema Naturæ," the number known to him personally, and the number recorded respectively from North America and from South America.

Of mammals, the whole number of species recorded is 190, of which threefourths are based on the descriptions of previous authors. Only 48 were American, 12 from North America and 36 from South America. The 5 North American mammals known to Linnæus from specimens were the raccoon, star-nosed mole, common mole, flying squirrel and chipmunk. The number of species at present known from North America is 600, excluding subspecies. The number for the world, including the extinct as well as the living, is about 10,000 as against less than 200 recorded by Linnæus.

Of birds, about 925 are recorded of the 15,000 known to-day. The 200 known from America are divided about equally between North America and South America, only 50 of which were described from specimens.

The amphibia and reptiles number collectively about 250, of which about one-third are American, 40 per cent of the latter being North American and 60 per cent South American. The North American include 3 salamanders, the box-turtle, the six-lined lizard, the blue-tailed lizard and 14