XIII RANGE OF OTTERS 441 
the claws upon the hind-feet are flattened and somewhat  nail- 
like. There are about ten species, but of course, as is so 
universally the case, a great many more names have been given. 
The molar formula is like that of Hnhydris save that there is an 
extra premolar in the upper jaw. There are fourteen pairs of ribs, 
of which eleven pairs reach the ten-joimted sternum. The caudals 
are twenty-three. The Cape Otter, the “ clawless” Otter, has been 
separated as a genus donyx. So too has the South American 
Pteronura brasiliensis. But 1 neither case is the separation allowed 
by Mr. Thomas in a recent revision of the genus.' The latter 
species has the reputation of being very fierce, and is known in 
Fic. 223.—Otter. Lutra vulgaris. x}. 
Uruguay by the name of “ Lobo de pecho blanco.” The British 
species, L. vulgaris, reaches a length of 2 feet or so, with a tail of 
16 inches; it ranges over the whole of Europe and a large 
portion of Asia. This Otter often burrows in the banks of the 
streams which it frequents; and in the burrow in March or April 
the female brings forth her young, three to five in number. It 
will also frequent the sea-coast. 
Fossil Mustelidae. — Besides a number of the existing 
genera there are fossil members of this family which cannot be 
referred to existing genera. These latter extend back into time 
as far as the Eocene.  Stenoplesictis, one of these Eocene forms 
reterable to the sub-family Mustelinae, is to be distinguished 
1 <<Preliminary Notes on the Characters and Synonymy of the different Species 
of Otter,” Proc. Zool. Soc. 1889. p. 190. 
