. Contributions to a revision of the North American beavers, otters and fishers. Beavers; Otters; Fishers. NOTES ON THE OF THE WHITE RIVER OLIGOCENE. 363 Miacis utntensis Osborn. Bull. Am. Mus. Nat. Hist. N. ¥., Vol. vn, p. 77. Size rather less than that of D. hartshomianus; upper sectorial relatively small and tubercular molars large ; premolars short and thick. Measurements. MM. Length, pi to ni5- inclusive 37 P 3 length 7 PA length 11 P* width 11 M l length 11 Mi-width 1G M i length 9 M-2- width Fig. A.—First upper molar of the left side : 1, of ? Miacis uintensis. 2, of Daphxn
. Contributions to a revision of the North American beavers, otters and fishers. Beavers; Otters; Fishers. NOTES ON THE OF THE WHITE RIVER OLIGOCENE. 363 Miacis utntensis Osborn. Bull. Am. Mus. Nat. Hist. N. ¥., Vol. vn, p. 77. Size rather less than that of D. hartshomianus; upper sectorial relatively small and tubercular molars large ; premolars short and thick. Measurements. MM. Length, pi to ni5- inclusive 37 P 3 length 7 PA length 11 P* width 11 M l length 11 Mi-width 1G M i length 9 M-2- width Fig. A.—First upper molar of the left side : 1, of ? Miacis uintensis. 2, of Daphxnus harlsTiormanns. 3, of Canis lalrans. .r, cusp usually regarded as the protocone. If Iliads be rightly regarded as having a place in the canine phylum, then the structure of its upper tubercular molars is of great interest and will require a revis- ion of the current views concerning the homologies of the cusps in the upper molars of the dogs. In Canis, according to the usual interpretation, m A is composed of two external cusps, the para- and metacones, and at the apex of the triangle of which the para- and metacones form the base, an unpaired internal cusp, the protocone, with the proto- and metaconules on the anterior and posterior sides of the triangle respectively. Internal and somewhat posterior to the protocone is a large crescentic cusp, which is commonly regarded as an enlargement of the cingulum, although in unworn teeth a faint cingulum may be traced all around this crescentic cusp and is continuous with the prominent cin- gulum which bounds the anterior wall of the crown. If this interpretation of the cusps be correct, and further, if Miacis is ancestral to the Can idee, them m -1 in the Uinta genus is without a 'protocone and has only the para- and metacones, minute conules and the large inner crescentic cusp. It seems much more rational to conclude that the lat- ter is really the protocone and that the cusp which has been so named in Canis i^ an additional el
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectotters, bookyear1898
