402 CALLORHINUS URSINUS NORTHERN FUR SEAL. 



at which age they seek the males for sexual intercourse. On 

 the other hand, the males return the following year with the 

 mature females. On their arrival they land on the island and 

 pass some distance inland, where they repose in large herds 

 during the breeding-season, and linger about the island until 

 after the females and their young are gone. They continue to 

 return, each year, arriving earlier as they approach to maturity, 

 until old enough to become beachmasters. But the young- 

 females, as already stated, are not seen in numbers until they 

 are three years old, when they arrive about the height of the 

 breeding-season. Considerable numbers land on the breeding- 

 places, but a larger portion are covered by the males before 

 they have time to land. In the females there are no definite 

 external indications of age as there are in the males, and in as- 

 signing the age of three years I have accepted the judgment of 

 the natives, who are familiar with every phase of Seal life, and 

 are governed mainly in their opinion by the appearance of the 

 teeth. In the few I have had killed from time to time for ex- 

 amination the differences have been pointed out to me, but I do 

 not consider myself competent to judge, and in the absence of 

 more definite evidence I accept the statements of the natives. 

 At this age they weigh about forty-five pounds, are of a steel- 

 gray color on the back, with pearly white breast and belly, the 

 gray of the back gradually shading into the white on the sides, 

 and their coat has a very soft, velvety appearance. When they 

 return the following year to give birth to their first young they 

 average sixty pounds, and the color of the back is of a deeper 

 shade and extends lower down on the sides. They still con- 

 tinue to grow for two or three years, and attain an average 

 weight of eighty pounds. At six or seven years old the color 

 of the back has become brown and extends to the belly, which 

 is then only a few shades lighter than the back. When the 

 young females first land their color is bright and soft, but in 

 two or three days the white tint gradually becomes of a rusty 

 shade, so that when visiting the rookeries daily it is easy to dis- 

 tinguish the Seals that have just landed. After they have been 

 on shore ten days they become all of the same shade, and are 

 individually undistinguishable. As the females are never killed, 

 but are left to die from old age or natural causes, there are no 

 means of ascertaining their length of life. In exceptional cases 

 they become barren and haul up with the young males. 



