TWO CETACEANS PROM TRAVANCORE. 41 



With regard to the second specimen (PI. B), I agree with Mr. Fer- 

 guson in assigning it to the genus Tursiops, in spite of the fact that it 

 differs from all the other species in the separation of the pterygoid 

 hones of the skull. Externally it agrees with Tursiops in the form of 

 the beak and fins, as well as in the general outline of the body, and the 

 number and characters of the teeth. The number of vertebra (61) is 

 also that of Tursiops (61 — 64), and of no other of the allied genera. 



Of the four species of Tursiops recognised by Mr. True,* the typical 

 T. tursio, in addition to the united pterygoids, differs by the colour of 

 the under-parts, which is either pale-grey or white, and the smaller 

 number of teeth (§§), the number of vertebrae being 64. The smaller 

 T. parvimanus, of the Adriatic, in which the teeth number §£ and the 

 vertebra 62, has also greyish-white under-parts. In the Australian 

 T. catalania the under-parts are likewise white. On the other hand, 

 Tursiops abusalam of the Red Sea comes nearer to the Trivandrum 

 dolphin, having |^ teeth and 61 vertebra, and showing flesh-coloured 

 markings mixed with green on the under-parts. The dark sea-green 

 of the upper-parts does not, however, accord with Mr. Ferguson's de- 

 scription ; and there is the aforesaid difference in the pterygoids. The 

 Pacific T. gilli is too imperfectly known to admit of comparison. 



On the whole, I think it advisable to regard the Trivandrum dolphin 

 as a new species of Tursiops, allied to T. abusalam (of which I have no 

 specimens for comparison), but distinguished by the divided pterygoids, 

 the blacker colour of the upper-parts and the more decided plumbeous 

 flesh-colour of the under-surface, which is marked with streaks instead 

 of spots. It may be appropriately named l\fergusoni % 



Mr. Ferguson has promised to present the skull to the British 

 Museum. When it arrives, I might publish a notice of its characters. 



Bull. IT. S. Mus., No. 3G ; p. 158 (1889). 



