26 



BULLETIN 36, UNITED STATES NATIONAL MU«EUM. 



In Cuvier's original description (Ann, du Museniu, xix, 1812, p. 9) no 

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

 description, however, and the figure afterwards published in the Osse- 

 mcntsfossiles, 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 s]:>ecies 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. reinivarcltii : 



Comparison of the length oj the leak in S. conqjressiis, etc., taken at 100 per cent., uith its 



xvidth at the middle. 



Collection. 



1. Leiden 



2. Liverpool 



3. Paris 



4. London (B. M.) 



5. London (B. M.) 



6. Liverpool 



7. Leiden 



8. Oxford 



P. Oxford 



10. Liverpool 



11. Liverpool 



12. Liverpool 



13. London (B. M.) 



14. Leiden 



15. Leiden 



16. Oxford , 



17. Liverpool 



18. Leiden 



19. Liverpool 



20. London (B. M.). 



21. Liverpool 



22. London (B. M.). 



23. Liverpool 



24. Liverpool 



2.5. Leiden 



26. Norwich 



Number. 



24 



7,7,66,31.- 



rt3047 



346& 



346a 



24,2,63.... 



26 



XS(juy.).. 



1068 



19,11,62... 

 13,11,68,1. 



a 



346rf 



None (1) .. 

 None (2) .. 



1676 



23,1,04,2.. 



27 



21,5,02,1.. 



245rf 



12,7,69,1.. 



245c 



24,3,59,2.. 

 7,2,70,63.. 

 30 



Identification. 



Reinwardtii (?Typo) 



lloatratus 



Compressus 



Compressus (Type) 



Planiceps. 

 Tlostratus. 

 Rostratus. 



Compressus 

 ? Planiceps . . 

 ? Planiceps.. 

 Rostratus. .. 



? Planiceps 

 Frontatus . 

 Frontatus . 



Planiceps. 

 Frontatus 



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 in 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 loDgest rostrums have the greatest number of 

 teeth. 



In Cuvier's figure of the skull of JD. rostratus {Oss.foss., 4th ed., 183G, 

 pi. 222, fig. 7) the breadth of the ro.struni at the middle is 10.1 per cent. 



