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256

B I R D S

their relationship or pedigree be unravelled. Gadow’s system is given below. Newton’s Dictionary of Birds, 1893-96, is the latest standard work on ornithology. Under its various headings, anatomical, bionomic, geographical, historical, and systematic, and in the 120 pages of the introduction, it contains condensed accounts of, or at least references to, wellnigh everything which pertains to ornitho- logy,—H. Seebohm. Classification of Birds. London, 1890. Based upon Fuerbringer and not a genetic system, with “diagnoses ” based upon mechanical combinations of striking, but often arbitrarily selected characters.—B. B. Sharpe. A Bcview of Attempts to Classify Birds. Budapest, 1891. Likewise based upon Fuerbringer and not genetic. Simply a linear arrangement of wellselected groups, with enumeration of anatomical and bionomic characters selected from Stejneger and Seebohm. Dr Sharpe is also the author of by far the greater number of volumes of the Cat. Birds, Brit. Mus., a gigantic descriptive work which was finished in 1898.—St. G. Mivart. The Elements of Ornithology. London, 1892.—F. E. Beddard. Structure and Classification of Birds. London, 1898.—H. H. Evans. Birds, Cambridge Natural History, vol. ix. London, 1899. Much had naturally been expected from the study of fossil birds, but, so far as the making of classifications is concerned, they have proved rather a source of Palmperplexities. So long as the characters of new on o ogy. £osgQg are on]y 0f specific and generic value, it is mostly possible to assign the birds to their proper place, but when these characters indicate new Families or Sub-orders, for instance Hesperornithes, Ichthyornithes, Palcelodi, their owners are put outside the more tersely constructed classifications applicable to modern birds. It is no exaggeration to say that the genus, often even the species, can be determined from almost any recent bone, but in the case of Miocene, and still more, of Eocene fossils, we have often to deal with strange Families, which either represent an extinct side branch, or which connect several recent Groups with each other. Our artificially-established classifications collapse whilst we gain further insight into the mutual affinities of the existing Groups. Of course this must be so if evolution is true. But it also follows that, if every extinct and recent bird were known, neither Species, nor Genera, nor Families, nor Orders could be defined. We should be able to construct the pedigree of every Group, in other words, the gigantic natural system, but there would be no classification. Much light has also been thrown by fossil birds upon the study of geographical distribution. The key to the distribution of recent groups lies in that of the extinct forms. Not only have many absolutely new Families been discovered, but many kinds of modern birds are now known to have existed also in countries where they are now extinct. There were, for instance, trogons, secretary-birds, parrots, and other now Ethiopian forms in Miocene France. Ostriches, undistinguishable from Struthio, have been found in Samos and in the Sivalik Hills. The proper study of fossil birds may be said to have begun with the late A. Milne-Edwards, whose magnificent Oiseaux fossiles de la France was published from 1867-71. This work deals chiefly with mid-Tertiary forms. A new impetus was given by the late O. Marsh, who, as we have seen, since 1870 discovered a great number of bird remains in the Cretaceous strata of A orth America. The most important result is the proof that until the end of the Cretaceous epoch most, if not all, birds were still possessed of teeth. In 1877 a second specimen of Archaeopteryx was discovered. This Berlin specimen supplements our knowledge of that in the British Museum. It has been fully described by W. Dames in Palceontolog. Ahhandl. bd. ii. pt. 3, Beilin, 1884. Archaeopteryx is already a typical bird, possessed of the power of flight, owing to the transformation of its anterior extremities into typically avine _ wings with remiges. It still retains various very archaic characters,

e.g., teeth, amphicoelous vertebrae, those of the tail numbering about twenty, and although they carry about twelve pairs of well-developed rectrices, they are not yet condensed into a pygostyle. The latter character is, however, of no absolutely distinctive value, it being only peculiar to the majority of the Carinatce. Hence the inadvisability of retaining the term Saururce in opposition to Ornithurce. Archaeopteryx has only slightly narrowed the enormous gap between birds and reptiles. The attempt to look for the ancestors of birds among the Pterosauria is as futile as the various attempts to seek them amongst any of the known groups of Dinosauria. A great number of other fossil birds has been described from various parts of the world, notably by Cope, Fraas, Lund, Lydekker, Seeley, &c., but the most recent and bewildering mass of new forms was discovered by Ameghiuo chiefly in mid-Tertiary strata of Argentina (see Revista Argentina de Historia Natural, i. 1891; Boletin. del Inst. Geograf. Argentin. xv., 1895; and the sumptuous publication in the Anales del Museo de la Plata, 1891, by F. P. Moreno and A. Mercerat). Many of the bones indicate birds of gigantic size, and they were collectively called Stereornithes by Moreno, who not unnaturally considered them as allied to the Ratitae. Some of these birds were undoubtedly flightless. The most remarkable genus is Phororhacos, with an enormous skull of more than two feet in length. Benewed investigation by Mr Andrews of some of the material now in the British Museum has shown that Stereornithes has to be abolished as a taxonomic group. Phororhacos belongs to the early Gruiformes, perhaps with Pelecyornis and Liornis. Dryornis seems to belong to the Cathartae, anyhow to the Falconiformes, while Mesembriornis is a direct forerunner of the present Rheae. In conclusion, the present writer gives his classification of birds in which the extinct forms have been intercalated so far as possible. The few characters assigned to the various groups are sufficiently diagnostic when taken together, although they are not always those upon which the classification has been established :— Class AYES. I. Sub-class Archaeornithes.—The three fingers and their metacarpals remain separate, each with a claw. Well-developed remiges. Both jaws with alveolar teeth. Amphicoelous. Caudal vertebrae more than thirteen, without a pygostyle, but with about twelve pairs of rectrices. Archaeopteryx, A. lithographica, s. macroura, and A. siemensi, two specimens from the upper Oolite of Solenhofen, Bavaria. II. Sub-class Neornithes.—Metacarpals fused. Second finger the longest. Not more than thirteen caudal vertebrae. I. Division Ratita:.—Terrestrial, flightless. Without sternal keel. Quadrate bone with single proximal knob. Without pygostyle. Coracoid and scapula fused. Compound Rhamphotheca. Adult without apteria. With copulatory organ. A collective polyphyletic or heterogeneous group, originally cosmopolitan; with certainty existing since the Miocene. 1. Order Struthiones.—With pubic symphysis. Two toes only, third and fourth. Struthio, ostrich, Miocene of Samos, Pliocene of north-west India, now Africa and Arabia. 2. Order Rheae.—With long ischiadic symphysis. Three toes. Mesembriornis, miocene or pliocene of Argentina. Ehea, South America. 3. Order Casuarii.—Three toes. Aftershaft as long as the other half. Casuarius and Dromceus, Australian region. Hypselornis, Pliocene of Sivalik Hills. 4. Order Apteryges.—Four toes. Bill long and slender. New Zealand. 5. Order Dincrnithes.—Three or four toes. Bill short. Anterior