THE SOUTHERN SEA LION 135 



the jugal is fused to the zygomatic process of the maxilla and the line of fusion becomes 

 obliterated. The teeth show marked wear and the canines are conspicuous for their 

 length ; but the pulp cavity is still open in the canines of two skulls at least — nos. 478 

 and 480. 



The average size of this group with regard both to the length of the body and length 

 and other dimensions of the skull is greater than in any other group, and I have never 

 seen cows which could reasonably be supposed to be larger than in these animals. It 

 may therefore be asserted that the tenth year group includes animals of the maximum 

 size for the female of Otaria byronia. The greatest body length is 195-6 cm., and the 

 greatest skull length 276 mm. It is a peculiar fact that in some of these skulls the floor 

 of the sella turcica becomes of almost paper thinness. 



The approximation to a normal growth curve of the graph in Fig. 1 may be observed. 



REPRODUCTION 



ANATOMY OF THE REPRODUCTIVE ORGANS 

 Male. The anatomy of the reproductive system of the male has been fully described 

 by Murie (1874) and need not be remarked on here except to state that he found that the 

 prostate is small and Cowper's glands, if present, are little more than vestigial. His 

 specimen was an immature male, presumably in its fourth year and 170 cm. in length. 

 Female. The ovaries have a rounded bean shape and increase in size with advancing 

 age (Fig. 3). The increase is not necessarily due to the presence of corpora lutea, although 

 there is almost invariably a structure of that nature present in one or other of the ovaries. 

 There is an actual increase in the amount of ovarian stroma, due, it may be suggested, 

 to previous activity. The surface is quite smooth in the young animal, e.g. no. 450, and 

 becomes very slightly pitted with advancing age. The smallest pair of ovaries is that of 

 no. 458, with weights of 3-5 and 2-5 = 6 g., and the largest pair from a non-pregnant 

 cow are those of no. 478, 31 and 28 = 59 g- Even wnen ri P e the f° mcle does not project 

 appreciably from the surface of the ovary, but its presence is indicated by a darkening 

 of the wall at the place where rupture will take place, and the thinning of the tissues 

 enables the follicular fluid to become perceptible (the macula). 



When the corpus luteum is formed it does not project from the surface, but the entire 

 ovary is enlarged by its presence; the smooth surface of the ovary is maintained. 

 Corpora lutea disappear fairly rapidly ; in the whole series two are present in but six 

 cases and in only three others can the traces of a third be found (p. 144). 



Seal no. 510, which contained male twins, had two corpora lutea of pregnancy in the 

 appropriate side and in the other ovary was an old corpus luteum about 1 cm. in 

 longest diameter. The size of the largest corpus luteum in each animal is shown in 

 Table VIII ; the figures are those of the longest diameter, but these bodies are not usually 



exactly spherical. 



The ovary is enclosed in a capsule which communicates with the body cavity by a 

 small aperture, but immediately after ovulation the capsule is filled with liquor folliculi 

 so that at least at this period the aperture is almost or entirely non-functional. 



