OF 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 
fully 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. cit. 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 S. 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. 
enagrejslensth gon Siebert alt lolembs canal oa 4207 
Length of rostrum. . . Peete AS Mo Ite enstescy 3 ofll2'8 
Breadth of occipital Pecincni Sy iearhe) Barf Srl t2t? work) Bell 
Greatest height of occipital foramen . . . . . . .. . 18 
Breadth of occipital condyles . . . sole Dard Soho el! 
Greatest breadth of cranium at ae MEP TON meee. eae en ROL 
y¥2 
