1899.] on A SHAKK-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 me that the Peruvian and ChiUan 

 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. 



[Eeceived September 7, 1899.] 



In 1893 I described and figured ' an imperfect skull of a Shark- 

 toothed Dolphin from a Tertiary deposit at Chubut, Patagonia, 

 which was clearly generically distinct from Squcdodon, and seemed 

 to me to require a new name. I accordingly suggested the title 

 of Prosqualodon australis. Erom Sqitalodon this Dolphin evidently 

 differed in the smaller number of teeth, and apparently in the 

 shorter and more laterally curved lower jaw. Moreover, 1 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 my attention 

 has been directed by Mr. 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 Cogia 

 breviceps, so far as proportion is concerned. It agrees in all 

 respects with the type skull ; and there is one detached tooth re- 

 maining, which is of the same Squalodont type 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 com- 

 paratively but little imperfect on the upper surface. On 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 man- 

 dibular ramus is preserved. 



' An. Mus. La Plata,— Pal. Arg. vol. ii. art. 2, p. 8, pi. iv. (1893). 



