OP THE CHINESE "WHITE DOLPHIN. 153 



The genus Delphinus, as restricted by F. Cuvier and Rapp, contains numerous species, 

 presenting great diversity of anatomical characters. Unfortunately the requisite mate- 

 rials are still wanting for making a satisfactory arrangement of the group, as complete 

 skeletons of but very few species are preserved in museums, and fewer still have been 

 folly described. Dr. Gray has arranged the species in numerous genera and sections, 

 founded on variations in the characters of the cranium, the only part at present available 

 for the purpose. Although this arrangement is very convenient for the purposes of prac- 

 tical zoology, it is necessarily provisional, and awaits a knowledge of the remainder of the 

 organization to determine its scientific status. On comparing the skull of the present 

 specimen with the description in Dr. Gray's last ' Synopsis' (1868), aided by an examina- 

 tion of the originals in the British Museum, it is perfectly evident that it belongs to a 

 species there undescribed. Its exact position among the numerous divisions of the 

 family can, however, be clearly determined. It belongs to the Tribe Stenonina, and 

 genus Steno (loc. tit. p. 5), characterized by having the " beak of the skull compressed, 

 higher than broad. Symphysis of the lower jaw long." In size and other characters 

 the skull corresponds with Section A of that genus, comprising S. frontalis and S. com- 

 pressus ; but in the number and size of the teeth it is intermediate between this section 

 and the next, as it has exactly three teeth in each inch of the alveolar margin, whereas 

 in Dr. Gray's first section there are two, in his second (comprising S. capensis and 

 S. lentiginosus) four in each inch. 



This determination of the position of the Chinese White Dolphin, according to its 

 cranial characters, makes an account of its complete osteology particularly important, 

 as no skeleton of any member of this well-marked group (genus Steno, Gray) has 

 hitherto been described or figured. 



The Cranium (as seen in Plates XVII. and XVIII.) presents the well-known general 

 characters of the allied forms. It closely agrees with 8. frontatus and S. compressus of 

 the British Museum in size, but differs from them in the rostrum being broader at the 

 base and tapering gradually towards the middle, and especially in the form of the 

 pterygoid bones and in the greater number and smaller size of the teeth. In the form 

 of the rostrum and number of teeth it approaches to S. lentiginosus, Ow., from the 

 Indian seas, but differs from this species in its superior size, and also in the form of the 

 pterygoids. 



The principal dimensions of the skull are as follows : — 



inches. 



Entire length 20'7 



Length of rostrum 12-8 



Breadth of occipital foramen 1*7 



Greatest height of occipital foramen 1*8 



Breadth of occipital condyles 4T 



Greatest breadth of cranium at parietal region 6-4 



y2 



