114 ME. W. H. FLO WEE ON THE OSTEOLOGY 0¥ 



1. Physeterince, characterized by the numerous teeth in the lower jaw, and having 



no distinct lachrymal bone, including the genera Pkyseter and Kogia (Gray)*. 



2. Zijihiince, 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 Platanistidoe must each be placed in a distinct 

 subfamily, characterized thus : — 



1. Platanistinw. 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. IniincE. MaxOlary 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 structui'e ; 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 Belphinidce 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- 

 tebrae. As these two animals are in almost every part of theii- skeleton nearly identical, 

 even to the number of the vertebrae 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 PlatanistidcB. Among 

 ^he 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. Phocmna and Neomeris stand by 

 themselves in the form of their teeth and certain cranial characters. Orca is distin- 

 guished from all the others by its excessively broad manus, and Globiocephalus by the 

 extreme length and narrowness of the same member. Belphinus 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 Eupliysetes (WaU. Descr. New Sperm Whale, 

 &c., 1851); but Gray's name (Zool. Erebus and Terror, 1846) clearly has the priority. 



