274 DISCOVERY REPORTS 



PHYSICAL CHARACTERS 



In his monograph of the North American Pinnipedes J. A. Allen (1880) remarks on 

 the great range of individual and age variation in the order, and Otaria furnishes no 

 exception. 



There are six stages in the life of this species, the first five each corresponding to a 

 year of the animal's life. Even after breeding it is possible that growth and development 

 continue, although the degree to which they do so is subject to the individual idiosyncrasy 

 of the particular animal. 



In deciding the age of one of these seals the principal characters which have to be 

 considered are the following: 



(i) Length of the animal from tip of snout to tip of tail, and, associated with this, 

 bodily development. 



(2) Coat colour. 



(3) Length of skull in a straight line from the front of the premaxillae to the back 

 of the occipital condyles — the condylo-basal length. 



(4) Proportion of the skull length to the total length of the body. 



(5) Proportions of various skull measurements to the length of the skull. 



(6) Osteological development. 



(7) Dental development. 



(8) Condition of the reproductive glands, when they can be examined. 



It is unnecessary to give a description of the external form of the sea lion, which is 

 sufficiently familiar (Figs, i, 2; Plates II, III, VII), although it may not be appreciated 

 how great is the contrast in development in the adult male between the enormous 

 fore-part of the body and the comparatively feeble hind-quarters. There is a great 

 difl'erence in size between the sexes ; the average length of nine specimens of the adult 

 male was 234 cm., and of eleven adult females 179 cm. The weight of an adult male 

 collected by the ' Scotia ' was over 1 500 lb., that of the female is of course very much less. 



Murie (1872 and 1874) has given a detailed account of the anatomy based on a young 

 male from the collection of the Zoological Society. 



BODY MEASUREMENTS 

 Length of the animal and body development {Table II) 



Newly born. There is only one specimen of this stage in the collection, that of a very 

 young male, which if not exactly newly born could not have been more than a few 

 days old; the total length was 83-8 cm. This pup presented the usual characters of 

 the very young mammal, namely a slightly made body and a large head. There appears 

 to be no external diff"erence between the sexes at this age. 



i^/r^/jrar (about six months old). Males 120-3 ^m., 10 specimens; females 1127 cm., 

 5 specimens. The males soon out-distance the females in the rapid period of growth 

 which is comprised in the first six months; during this time the males increase by 

 about 43 per cent and the females by 34 per cent (approximately). The single "newly 



