562 CONCLUSIONS. 
that from them another group gradually arose, which had broader 
webs on the hind feet. This group may be called /ong-tailed an- 
cestors of fin-tailed otters, for the fin-tailed otter (Lutra Sanbachu 
Gray) is a still living descendant of them. The tail of this animal 
is shorter than that of its ancestors, longer, however, than that of 
the otters (Zutra), surpassing one third of the animal’s total length. 
Moreover it is somewhat flattened and shows on its hindmost half 
lateral fin-like dilatations. The change was great enough for zoolo- 
gists to place the animal into a new genus: Péeronura Gray. Its 
ancestors, however, were not provided with these lateral fin-like 
dilatations on the tail. 
Some of these long-tailed ancestors of the jfin-tailed otter which 
in their migration had reached the sea-shore, probably by following 
the course of rivers, began to accustom themselves to eat sea-fish , 
and ended by feeding on them exclusively. The sea-water became 
their home, and their resting places and nests were found on the 
strand, and among sea-weed; they seldom came ashore to sleep or 
to sun themselves. Besides on sea-fish, they fed on crabs, lobsters, 
mussels, and some sea-weed. They left off eating poultry, frogs, 
and rats. The long tail was of great profit, as they used it as a 
rudder and as propelling organ in swimming with vertical undu- 
lations. Of course those individuals which were the best adapted 
to this new manner of living, survived the less privileged by nature, 
and so a group gradually arose which had a sharper dentition, 
and smaller ears; the skin was also changed to the must valuable 
fur, the toes of the hind-legs had become more webbed, and 
with such legs the animals could swim more easily; those of the 
fore-limbs had sharper nails, and with such nails the animals could 
more easily crawl upon the rocks; the eyes were larger, and with 
such eyes the owners could see better in great and dark depths, 
and in the sea-water near the shore, which is commonly troubled ; 
the whiskers were longer and stronger, consequently the upper-lips, 
in which these whiskers were planted and which contained numer- 
ous and thick sensorial nerves, were very thick, and with such 
whiskers the animals could exceedingly well touch and feel when 
searching for their food between stones and sea-weed, and in the 
sandy bottom. The face resembled but little more that of the otters 
and fin-tailed otters, and the large eyes and shorter ears gave it a 
slight resemblance to seals. This group may be called /ong-tailed 
ancestors of sea-otters, for our sea-otters (Lutra lutris L.) are still 
living descendants of them. But as these animals have accustomed 
