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Show 1901.] DOLPHIN PROM BORNEO. 89 The skull (text-fig. 11) at once shows that the specimen belongs to the Sotaha-Steno group of Dolphins, to which comparison may accordingly be restricted. The pterygoids are widely separated trom one another in the middle line ; and the teeth, which are of medium size, smooth, and antero-posteriorly compressed, number 36 m the upper, and 34 iu the lower jaw. Unfortunately the skeleton is somewhat incomplete posteriorly, so that the total number of vertebrae cannot be ascertained. There are, however, 30 in the precaudal series. Text-fig. 11. A B Lower view (A) and lateral view (13) of the skull of Sotalia borneensis. PL Pterygoid. As regards the distinction between Steno and Sotalia, Messrs. Flower1 and True2 included all the forms with divided pterygoids in the latter, and those with conjoint pterygoids in the former. Mr. Blanford3, however, has transferred the three Indian species S. plumbeus, S. pemiger, and S. lentiginoses from Sotalia to Steno, 1 List of Cetacea in Brit. Mus. pp. 31 & 32 (1885). 2 Bull. U. S. Nat. Mus. No. 36, pp. 153 & 156 (183U). 3 Fauna of Brit. India: Mammalia, pp. 582-585. |