482 PROF. FLOWER ON THE DELPHINID,^. [NoV. 20, 



in 1872, not the slightest difference can be detected, either in size 

 or form or in the characters of the teeth. 



It follows from what has just been said, that of the section (or 

 genus) called Tursiops there are two distinct forms as indicated by 

 the skulls : — 



1. T. tursio, including those that have been named metis, evry- 

 nome, cymodice, adunctts, and gillii, some of which may be specifically 

 distinct, but, if so, are very closely allied, and still require defi- 

 nite elucidation of their characters, the principal differences ob- 

 served in the skulls depending on the comparative breadth of 

 the rostrum, a character much influenced by sex. T. adunctts 

 {T. abusalam, Gray) differs from the rest only in its superior 

 size. 



2. T. caialania, of smaller size than any of the others, and with 

 smaller and more numerous teeth. There is truth in the remark 

 with which Dr. Gray concludes his original descrijjtiou of this 

 species. After com})aring it with others of the group, he says : — 

 "It is not easy to point out the distinction of these species in 

 words ; but there cannot be a doubt about them when they are com- 

 pared together " '. 



The Dolphins of other groups which present the nearest resem- 

 blance to Tursiops, both in external and cranial characters, are those 

 of the section of the genus Glyinenia to which C. obscura belongs. 



Steno. 



Steno, Gray, Zool. Erebus & Terror, p. 43 (1846). 



GlypJddelphis, Gervais, Zool. et Pal. Franpaises, p. 301 (18.59). 



This group contains also some comparatively large forms of Dol- 

 phins, but which differ greatly from the last in the form of the skull. 

 There are no lateral grooves on the palate, and the pterygoid bones 

 are of the normal form, meeting in the middle line (sec fig. 6). The 

 rostrum is long, narrow, compressed, and very distinct from the 

 cranium. The symphysis of the mandible is longer than in any of 

 the other De/phinidce, exceeding one fourth of the length of the 

 ramus. Teeth 21 to 25 on each side of each jaw, of comparatively 

 large size (5-6 millim. in diameter at base of crown), and in most, if 

 not all the species, with their surfaces roughened by fine irregular 

 longitudinal grooves (which are in a great measure effaced in old 

 individuals) not seen in other Dolphins, and whence the name G/y- 

 phidelphis proposed by Gervais for the section. 



The type of this group is known by skulls only, which are very 

 common in museums, but, as far as I am aware, no skeleton of the 

 species has ever been preserved, and its external characters are most 

 imperfectly, if at all, known. 



The first published intimation of the existence of the speci- 

 mens upon which the species was idtinialely founded is contained in 

 Cuvier's " Rapport sur diverses Cetaces '" &c., in the 'Annales du 



1 P. Z. S. 18r>2, p. 145. 



