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Show 1899.] ON A SHARK-TOOTHED DOLPHIN FROM PATAGONIA. 919 Deer, exhibit a reddish phase in summer, and a more greyish (blue) tint in winter. The Chilian Guemal was originally named from specimens obtained in the Andes of the country from which it takes its popular title ; probably on the east side of the main range. I can find no reason for separating the Patagonian animal, even racially. It has sometimes occurred to m e that the Peruvian and Chilian Guemals might be nothing more than local forms of one widely-spread species ; but the important points of difference indicated above leave little doubt as to the propriety of regarding them in the light of separate species. 5. On the Skull of a Shark-toothed Dolphin from Patagonia. By R. LYDEKKER. [Received September 7, 1899.] In 1893 I described and figuredl an imperfect skull of a Shark-toothed Dolphin from a Tertiary deposit at Chubut, Patagonia, which was clearly generically distinct from Squalodon, and seemed to m e to require a new name. I accordingly suggested the title of Prosqualodon australis. Prom Squalodon this Dolphin evidently differed in the smaller number of teeth, and apparently in the shorter and more laterally curved lower jaw. Moreover, I came to the conclusion that the nasals, instead of forming mere nodules of bone lying in depressions of the frontals, were of triangular form, and to a certain small extent roofed over the base of the nose-cavity. Unfortunately, the extremity of the rostrum was so broken as to preclude the possibility of estimating the total length of the skull. This deficiency is supplied by a skull from the same deposit recently acquired by the British Museum, to which m y attention has been directed by M r . C. W . Andrews. This specimen has a general resemblance to the skulls of the short-beaked Dolphins of the present day, such as Phoccena, Grampus, Globiceps, &c. In size it apparently comes very close to the skull of Pseudorca crassidens, but is relatively shorter, and therefore more like that of Cocjia breviceps, so far as proportion is concerned. It agrees in all respects with the type skull; and there is one detached tooth remaining, which is of the same Squalodonttype as those of the latter. With the exception of a certain amount of damage to the region of the blow-hole, the new skull, in spite of numerous fractures, is comparatively but little imperfect on the upper surface. O n the under surface the pterygoids, which afford such characteristic features in differentiating the skulls of the existing Dolphins, are wanting. Of the lower jaw only the greater portion of the right mandibular ramus is preserved. > An. Mus. La Plata-Pal. Arg. vol. ii. art. 2, p. 8, pl. iv. (1893). |
