46 EDWARD A. WILSON. 



Ill our own series the teeth of skull No. 1 arc exceptionally strong and well- 

 developed throughout, c^uite regular, and firmly rooted. The same remarks apply 

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

 and to those of No. 4G. 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 l)ut 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 l)e a persistent milk tooth. In skull No. 28 precisely 

 the same apparent persistence t)f a milk tooth is to he 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 teetli 

 loose, and when the skull is cleaned, they will l)e found in some cases to have no liony 

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

 leave no trace of their existence.* 



Ommatojyhoca has apparently the same range and distribution as Lohodon, 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 Ommatophoca 

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

 l)Oth, and it is not easy to see why in numbers Lohodon should be so very far ahead. 



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

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

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

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

 the Cystophorldnce than with any of the Stenorhincldnce. 



In all the seals, with liut 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 Phoclnce, grouped mainly upon 



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



3 3 ..2 — 2. 



variation of I. ; then an example of Phoca foetida with I. as a variation oi 



2 — 2 • ^ 1 — 1 



3 o 



I. • then, too, in the StimorJunclnncB, two examples of Monachus albivcnter, one 



with I. ^ , the other with I. ^^ " as variations of I. " ^, and an example of 



" "^ 2 2 2 2 



Lohodon with I. 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 followmg discrepant statements concerning 

 vestigial teeth in Whales. Trof. M. Weber (Die Saugetiere, 1904, p. .578) says of the Physeterinfe :— " 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 onl\ in the adult, they may be seen in tlie young animal upon removing the soft parts from the 

 interior of the jaw." 



