114 MR. W. H. FLOWER ON THE OSTEOLOGY OF 
1. Physeterine, characterized by the numerous teeth in the lower jaw, and having 
no distinct lachrymal bone, including the genera Physeter and Kogia (Gray)*. 
2. Ziphiine, with only one or two pairs of teeth in the lower jaw (besides the ru- 
dimentary concealed teeth), and a distinct lachrymal bone. This includes 
Hyperoodon, Berardius, Ziphius, Micropteron, Dioplodon, and several extinct 
forms. 
II. The two best-known genera of the Platanistide must each be placed in a distinct 
subfamily, characterized thus :— 
1. Platanistine. Maxillary bones supporting large bony incurved crests. No 
cingulum or tubercle at the base of the crown of the teeth. Pectoral fins 
truncated. Visual organs rudimentary. External respiratory aperture longi- 
tudinal, linear. 
2. Iniine. Maxillary crests absent, or very slightly developed. Many of the 
teeth with a complete cingulum or a distinct tubercle at the base of the 
crown. Pectoral fin ovate, obtusely pointed. 
The position of Pontoporia cannot be definitely determined until more is known of 
its general structure; but as its cranial and dental characters accord most nearly with 
those of Inia, it may be placed provisionally in the same subfamily. 
III. Although the Delphinide present considerable diversity in the characters of their 
dentition, in the relative length of the rostral part of the skull, in the form and struc- 
ture of the pectoral limb, and in the form and size of the dorsal fin, it is by no means 
easy to subdivide them into natural groups. It is even difficult to define neatly the 
distinguishing characters of the genera, so much do they blend one into the other. 
__ The Narwhal and the Beluga appear to separate themselves from all the rest, by 
certain well-marked structural conditions, especially the characters of the cervical ver- 
tebre. As these two animals are in almost every part of their skeleton nearly identical, 
even to the number of the vertebra and phalanges, I am disposed to look upon the ex- 
ceptional dentition of the former as an aberration of secondary importance, and to unite 
the two genera into a distinct subfamily, placing it next to the Platanistide. Among 
the remaining genera, none stand out in equal prominence. We must either group 
them together in one subfamily or make almost as many subfamilies as there are genera. 
For the present I prefer adopting the former course. Phocena and Neomeris stand by 
themselves in the form of their teeth and certain cranial characters. Ovca is distin- 
guished from all the others by its excessively broad manus, and Globiocephalus by the 
extreme length and narrowness of the same member. Delphinus and its allies are charac- 
terized by the long narrow rostrum and numerous teeth. Each of these genera might 
* A genus quite distinct from Physeter. It has also been called Huphysetes (Wall. Descr. New Sperm Whale, 
&c., 1851); but Gray’s name (Zool. Erebus and Terror, 1846) clearly has the priority. 
