26 



BULLETIN 30, UNITED STATES NATIONAL ML'SEUiL 



In Ciivier's original description (Ann. du Museum, xix, 1812, p. D) no 

 single skull is mentioned, and the species, therefore, has no type. The 

 description, ho\Yever. and the figure afterwards published in the Osse- 

 menisfossiles, would suffice for the recognition of the species were it not 

 that others were subsequently erected on skulls closely resembling that 

 figured by Cuvier. 



The characters "which have been insisted upon as separating the dif- 

 ferent species relate to the width of the beak and the number of teeth. 

 In the first of these characters, as Professor Flower has already inti- 

 mated, there is a complete gradation. The following table shows the 

 gradation in twenty-six specimens in European museums, including the 

 type of S. compressus and probably also of S. rcimcardtii : 



Compariso)! of the hngih oj the healc in S. coinpressiis, etc., talicn at IQO per cent., with its 



width at the middle. 



Collection. 



1 . Leiden 



2. Liverpool 



3. Taris 



4. London (15. M.). 



5. London (15. M.). 

 C. Liverpool 



7. Leidon 



8. Oxford 



0. Oxford 



10. Liverpool 



11. Liverpool 



12. Liverpool 



13. London (B. M.). 



14. Leiden 



15. Leiden 



IC. Oxford 



17. Liverpool 



18. Leiden 



19. Liverpool 



20. London (15. M). 



21. Liverpool 



22. London (B. M.). 



23. Liverpool 



24. Liverpool 



25. Leiden 



26. Norwich 



Number. 



24 



7,7,06,31.. 

 «3047-;... 



346& 



346a 



24,2,63.... 



26 



X5(jiiv.).. 



1068 



19,11,62... 

 13,11,68,1. 



346 d 



None (1) . 

 None (2) . 



1676 



23,1,04,2. 



27 



21,5,62,1. 



245rf 



12,7,69,1. 



245 c 



24, 3, 59, 2. 

 7,2,70,63. 

 30 



Identification. 



Reimvardtii (?Type) 



llostratus 



Compressus 



Coiuijressiis (Type) 



Planiceps. 

 Rostratus. 

 Rostratus. 



Compressus 

 ? Planiceps.. 

 ? Planiceps.. 

 Rostratus. .. 



? Planiceps 

 Frontatus . 

 Frontatus . 



Planiceps . 

 Frontatus 



Propor- 

 tional 

 ■width of 



beak 

 at middle. 



Per cent. 

 11.5 

 12.0 



12.2 

 12.' 6 

 12.9 

 13. 2 

 13.3 

 13.5 

 14.3 

 14.3 

 14.5 

 14.7 

 1.5.5 

 1.5. 6 

 15.8 

 15.8 

 15.8 

 10.2 

 10.4 

 10.5 

 10.9 

 17.4 

 18.1 

 18.7 

 18.8 

 ?21. 



Length 

 of skull. 



Inches. 

 20. 47 

 21.0 

 19.5 

 20.5 

 20. 125 

 21.25 

 19.92 

 19.4 

 20.2 

 21.4 

 20.25 

 21.4 

 20.125 

 19.08 

 20.79 

 20.0 

 20.25 

 19.2 

 21.75 



20. 375 

 20.6 

 20.125 

 20.85 

 20.0 



21. 00 

 19.2 



Greatest num- 

 ber of teeth — 



Upper 

 jaw. 



Lower 

 jaw. 



A gradation so complete as this evidently renders any character drawn 

 from the proportions of the rostrum useless as an index of specific dis- 

 tinctness, and, unless others can be brought forward, the separation of 

 the skulls into different species is, of course, unwarranted. 



The slight variation iu the number of teeth has no significance, as the 

 table plainly shows. In all species of dolphins, as a general rule, the 

 individuals having the longest rostrums have the greatest number of 

 teeth. 



luCuvier's figure of the skull of T). rostratus {Oss.foss., 4th ed.,1836, 

 pi. 223, fig. 7) the breadth of tlie rostrum at the middle is 19.1 per cent. 



