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Show 1880.] DENTAL CHARACTERS OF THE CANID2E. 287 Thooids, side by side, from South Africa, through Central Asia, to India and North and South America; (2) the limitation of Otocyon to South Africa ; (3) the limitation of Aguarine Thooids to South America and North-east Asia, including Japan; (4) the limitation of the most specialized Thooids, namely the Wolves and the ordinary Foxes, to the Northern hemisphere; (5) the exclusion of Foxes from South America; (G) the distribution of Cyon, which curiously resembles that of the Tiger. If provinces of distribution were marked out by the Canidae, they would by no means correspond with those generally recognized. There is nothing peculiar about the Australian dog, while the American continent contains within itself all the chief types of Canine animals, except Otocyon. The presence of this form, with its ancient type of dentition, in South Africa is not improbably due to the fact that this region contains the remains of a very old Mammalian fauna. • VII. The morphological relations of the living Canidae are such as to suggest that they result from the gradual accumulation of small variations in the general direction of increase of size and of differentiation of the teeth, superinduced upon a primitive stock which presented the full microdont dentition of Otocyon. VIII. Though the palaeontological history of the Canidae is incomplete, the facts which are ascertained tend in the same direction. In skull and dentition, the older Tertiary Canidae either, as in the case of Cynodictis, resemble the less-differentiated Canidae, or, as in Amphicyon, present a third upper molar, such as occasionally exists in Canis cancrivorus. But if, as I suppose, Cynodictis and Amphicyon were preceded by forms having four molars above and below, they have yet to be discovered, as no Eocene mammals with four molars, except Opossums, have as yet been brought to light. IX. The primitive stock of the dogs, for which we thus have to seek in older Eocene or earlier deposits, is theoretically required to have been a pentadactyle plantigrade animal provided with clavicles and possibly with bony epipubes. Such an animal, if it existed now, would probably be regarded as an Insectivore with more or less marked didelphous affinities. In conclusion I desire to express my thanks to the President, to Dr. Gunther, and to Dr. Rolleston for the ready access afforded me to the abundant materials for the study of the Canidae in the Museum of the Roval College of Surgeons, the British Museum, and the Oxford ^Museum, to Sir Joseph Fayrer and to M r . Wood-Mason, of the Indian Museum at Calcutta, for the great trouble they have been good enough to take in supplying m e with specimens of Indian species, and to Professor Peters, of Berlin, for the loan of a skull of V. corsac. [P.S. I ought to mention that large additions have been made to this paper since it was read before the Society ; but I have deferred the consideration of the origin and relations of the domestic dogs until the evidence which I a m at present collecting is more complete. July 4th, 1880.] PROC ZOOL. Soc-1880, No. XIX. 19 |