410 JOURNAL, BOMBAY NATURAL IIISTORY SOCIETY, Vol. XV. 



agrees so well with the generally accepted definition of Tursiops, that the 

 species to which it belongs may be confidently assigned to that genus. It 

 is true that the number of vertebrae is three less than the minimum 

 hitherto regarded as distinctive of that genus ( ] ) ; but since in T. tursio 

 the number is 64, while in T, ahisalam it is 61, there is no good reason 

 why a third form with only 58 should not be included in the same 

 genus. The range of specific variation in regard to the dental and 

 vertebral formulas of the three species under consideration is indicated 

 by the following table : — 

 Tursiops tursio—^ 



Teeth, §§. 



Vertebra ; C. 7 ; D. 13 ; L. 17 ; Ga. 27= 64. 

 Tursiops abusalam — 



JL ©Gull . ~t> v» • 



Vertebra ; C. 7 ; D. 12 ; L. 16 ; Ca. 26= 61. 

 Present specimen — 



Teeth, |f. 



Vertebra ; C. 7; D. 12 ; L. 15 ; Ca. 21=58. 



It will be noticed that in the above-quoted description, the pterygoids 

 are stated to be divergent posteriorly, whereas in Tursiops they are 

 described as in contact throughout their length (-). On examination of 

 ihe skull, I find, however, that their bones have undergone absorption 

 -to a large extent, and their remaining portion is much fenestrated. 

 Their present posterior divergence is therefore, I consider, entirely due 

 to senile degeneration, and I have no doubt that when the animal was 

 younger they presented the form and relations characteristic of the genus. 



As regards general size and proportions, the number of the teeth, and 

 colour (especially the " elongated blotches of dark-lead colour" on the 

 under surface, so clearly indicated in the sketch), the Trevandrum 

 bottle-nose agrees so closely with the description of T. catatonia, that 

 there seems every reason for regarding it as referable to the same 

 species. It is true the sketch does not show the spotting on the flippers 

 mentioned in the description of the types of the latter, and also that 

 there the flippers and back-fin appear proportionately a little longer 

 in the Trevandrum specimen, but I cannot regard such differences as 

 of specific value ; they may vary, for instance, with age. 



(') See Trans. Bull. U. S. Mus. No. 30, p. 158 (1889). 



C 2 ) See W. H. Flower, Proc. Zool. Soc, London, 1888, p. 478, fig. 5. 



