SEXUAL AND INDIVIDUAL VARIATION. 637 



while in summer it is scarcely 24 pounds. Carroll,, however, 

 gives a much larger weight. He states that u when they are in 

 full flesh the weight of a male Harp Seal varies from 700 to 800 

 pounds," and that "when prime" the skin and fat alone will 

 weigh 200 pounds, and the same parts of a female 125 pounds. 

 He gives the weight of a Harp Seal when born as 6 to 8 pounds, 

 according to the age of the mother. At fifteen days old he says 

 the " skin and fat will weigh 40 to 45 pounds," and the carcass, 

 after the fat is taken off, about 15 pounds. When thirty days 

 old the weight of the skin and fat he says is only 30 pounds, 

 and at nine mouths old not more than 40 pounds, but at twelve 

 months is 90 pounds ; the young Seals, as stated by other ob- 

 servers, losing much of their fat on being left by their mothers 

 to secure their own food, although the general size continues 

 slowly to increase. 



SEXUAL AND INDIVIDUAL VARIATION, AND VARIATIONS DE- 

 PENDENT UPON AGE. The variations in size and color depend- 

 ent upon sex and age having been already noted, little remains 

 to be said in the present connection beyond a brief reference to 

 the skull. Here the age and sexual variations appear to be 

 strictly parallel with those already described in Plioca fceiida. 

 The purely individual variation is also similar in character, 

 except, so far as can be judged from the small series of skulls 

 before me, the variations in the teeth are less marked. The 

 subjoined table of measurements of skulls indicates the range 

 of variation in size and other features. None of the skulls are 

 positively marked for sex, but there seems to be little difficulty 

 in distinguishing the sex by the smaller size, weaker structure^ 

 narrower muzzle, and the much weaker dentition in what may 

 be doubtless safely assumed to be the female, since very old 

 skulls, strictly comparable as respects age, vary in just these 

 points. Female skulls appear to rarely exceed, or even quite 

 attain, a length of 200 mm., while old males range from about 

 210 mm. to 228 mm. 



