TERTIARY SIRENIANS. 
575 
living state; but Steller states that the animal sometimes attained a length of from 
25 to 30 feet. The girth of the body was 19 or 20 feet; and the estimated weight 
8000 lbs. 
Distribution and With the exception of a single rib from Altu, no remains of the 
Habits. northern sea-cow have been obtained elsewhere than on Barren and 
Copper Islands. It is, however, almost impossible to believe that such a large 
animal could always have had such a restricted distribution; and it is hence 
probable that, when discovered, this Sirenian was already on the wane, and that the 
Commander Islands were its last resorts from a more extended distribution. Not 
the least remarkable circumstance connected with this animal is that, although 
closely allied to the typical dugong, it should have inhabited such a cold and 
northerly region. 
At the time of its discovery by Behring’s party, the northern sea-cow was 
abundant in the bays and river-mouths of the Commander Islands, where it lived 
in herds of considerable size. It fed chiefly on seaweeds, and more especially on 
the tangle which grows so abundantly in the northern seas. It was described as a 
stupid, sluggish, and comparatively helpless animal, which was unable to dive, and 
was not unfrequently washed ashore by the waves. From its inability to dive, it 
was compelled to obtain its food in shallow water; and from being often unable to 
approach the shore during the storms of winter, the animal was generally in poor 
condition by the spring. 
Within nine years of its discovery, the northern sea-cow was 
exterminated on Copper Island; while on Behring Island it had 
become very scarce by 1763, and the last of its race appears to have been killed in 
the year 1767 or 1768. It was long thought that the creature was practically ex¬ 
terminated by Behring’s party during their sojourn of ten months on the island 
named after their leader. This, however, was not the case, as they killed but very 
few. Soon after the return of Behring’s crew to Kamschatka several expeditions 
were fitted out for the purpose of wintering on the Commander Islands and hunt¬ 
ing fur-bearing animals ; the sea-cows offering the inducement of an abundant 
supply of fresh food. Ships sailing to Alaska were also in the habit of touching 
at these islands to take in a supply of salted sea-cow meat. With such stupid and 
helpless habits as characterised the animal, it is no wonder that its complete extirpa¬ 
tion was soon accomplished. Generally the sea-cow was harpooned from a boat; 
but by approaching stealthily hunters were also enabled to kill them with lances 
as they lay asleep near the shore. 
Extermination. 
Tertiary Sirenians. 
Throughout a large portion of the Tertiary period various species of extinct 
Sirenians were common in Europe, and they have also been sparingly met with in 
England. The best known of these was the halithere ( Halitherium ), which forms 
in some respects a kind of connecting link between the manati and the dugong. 
It resembled the latter in having the extremities of the jaws deflected, and in the 
presence of a pair of tusks in the upper jaw; but its molar teeth were more like 
those of the manati, although with a pattern recalling that obtaining on the crowns 
