152 PROF. W. H. FLOWER ON THE ELEPHANT SEAL. [Jan. 4, 



The molars are reduced to the extreme of simplicity (see figs. 1 

 and 2, pp. 1.50, 151). Each has a single long, tapering root, shaped 

 somewhat like a carrot, having a thickened shoulder near the neck, 

 caused by the deposition of cementum, and which projects above the 

 alveolus in old animals. The root of the first upper molar is the 

 longest, measuring in the large skull as much as CO millims. Each of 

 the others is shoiter than the one in front of it, to the last, which is 

 not \infreqnently rudimentary or absent. In the present case there is 

 no trace even of a socket, on the left side ; though on the right side 

 there is a small shallow cavity, from which a tooth appears to have 

 been lost (fig. 1, *). In the lower jaw the roots are more equal, that of 

 the first being slightly the longest, and the filth nearly as large as 

 any of the others. This, however, is absent, as well as that of the 

 upper jaw in No. 2921, which has thus A teeth of the molar series, 

 all premolars, according to what is now known of their homologies. 

 The crowns, when young, present traces only of the division into 

 pointed cusps or lobes, so cliaracteristic of the molars of most Seals — 

 mere grooves upon the surface, becoming deeper towards the apex, 

 to which they converge, and marking off rudimentary cusps, more 

 distinct on the outer than the inner surface of the tooth. The fifth 

 molar in both upper and lower jaws is of more simple character than 

 the others, often only a simple cone. 



In animals soon after birth these teeth are crowded together, the 

 first being placed in contact with the canine. In this stage the teeth 

 consist of little more than the crow ns, the incisors and molars being all 

 equally developed and in their places, and the canines with their apices 

 only appearing above the level of the alveolus ; the roots are only 

 commencing to calcify ; but as they grow in length and width, not only 

 does each require more room, but they become separated from one 

 another by intervals, which are most extended in the oldest indivi- 

 duals. The five molars of a very young male (No. 3934 a) occupy a 

 space from before backwards of 44 millims. In the largest skull 

 (3921 a) the same teeth are spread over 1 16 millims. 



In an old skull in the Leiden Museum (of which, the hinder part 

 being broken away, 1 am not able to give the length) not only the 

 whole of the crowns, but even the necks, of all the molar teeth, except 

 the last upper one, have been worn away, and wliat appear at first sight 

 to be the crowns are merely rounded stumps of dentine and cementum, 

 of very much larger size than the real crowns of the teeth of the young 

 animal. 



The sexes even of the youngest specimens can be recognized by the 

 comparatively small sizes of the crowns of the canines in the females. 

 In the males there is some difference in this respect, as the following 

 figures (measurements in millimetres) show, though the variations 

 are comprised within certain limits : — 



