46 EDWARD A. WILSON. 



In our own series the teeth of skull No. 1 are exceptionally strong and well- 

 developed throughout, quite regular, and firmly rooted. The same remarks apply 

 also to the teeth of skull No. 14, but for the presence of a small additional incisor, 

 and to those of No. 46. The incisor teeth of No. 25, however, are most unusual. 

 They occur in two tiers, of which the outer four are the larger, and the inner four 

 minute. In skull No. 26 the teeth are all well developed but not well rooted. The 

 alveoli are shallow, and just outside and behind the first premolar on each side of the 

 lower jaw is what appears to be a persistent milk tooth. In skull No. 28 precisely 

 the same apparent persistence of a milk tooth is to be seen in a similar position on 

 each side of the upper jaw. 



In the fresh-killed animal it is quite a common thing to find all the cheek teeth 

 loose, and when the skull is cleaned, they will be found in some cases to have no bony 

 socket at all, being merely held in the fleshy gum ready to drop out sooner or later and 

 leave no trace of their existence.* 



Ominatophoca has apparently the same range and distribution as Lobodon, and no 

 doubt if both were dependent on the same food, there would be some struggle between 

 them for subsistence. But seeing that Lobodon lives on crustaceans, and Ominatophoca 

 mainly on cuttle-fish, and possibly some vegetable matter, there is obviously room for 

 both, and it is not easy to see why in numbers Lobodon should be so very far ahead. 



If we consider the position which Ominatophoca has been given in the later 

 classifications of the seals, we may doubt, I think, with some reason whether it has 

 really as much in common with the Stenorhinchince as has been claimed for it, and 

 whether it has not closer affinities, notwithstanding the number of its incisors, with 

 the Cystophorhince than with any of the Stenorhinchince. 



In all the seals, with but very few exceptions, the variation in the dentition is so 

 excessive, that one is led to doubt the advisability of laying so much importance on 

 this one feature. When one finds, for example, in the Pltocince, grouped mainly upon 



g g 



the number of their incisors, first an example of Phoca vitulina with I. '- - as a 



Q Q 2 2 



variation of I. - ; then an example of Phoca fcetida with I. - - as a variation of 



o o 



I. - ; then, too, in the Stenorhinchince, two examples of Monachus albiventer, one 



q o ^ 2 2 2 



with I. ' , the other with I. - , as variations of I. - , and an example of 



~ 2 2 2 2 2 



Lobodon with I. '- J as a variation of I. ' ( , and no less than four variations 

 2 1 ^ " 



* My attention has been drawn by Prof. F. Jeffrey Bell to the following discrepant statements concerning 

 vestigial teeth in Whales. Prof. M. Weber (Die Saugetiere, 1904, p. 578) says of the Physeterinee : " Zahne des 

 Oberkiefers rudimentar, brechen nicht durch"; but Bennett (Whaling Voy. Bound the Globe, Vol. II., 1840, 

 p. 163) says : " The upper jaw is not altogether toothless, as usually described. On the contrary, it has on 

 either side a short row of teeth, which, for the most part, are placed more interior than the depressions which 

 receive the teeth of the lower jaw; though they sometimes, also, occupy the bottom of those cavities. Their 

 entire length is three inches ; they are curved backwards, and elevated about half an inch above the soft parts, in 

 which they are deeply imbedded, having only a slight attachment to the maxillary bone. In two instances, I have 

 found their number to be eight on each side. They exist in both sexes of the Sperm Whale ; and although 

 visible externally only in the adult, they may be seen in the young animal upon removing the soft parts from the 

 interior of the jaw." 



