47 Bulletin American Museum of Natural History. [Vol. XVI, 



largest and the second posterior cusp the smallest ; sometimes 

 there are two points in front of the main cusp, making five 

 in all ; sometimes the last posterior cusp is obsolete or barely 

 indicated, its development greatly varying in different 

 specimens. In addition to the variations above noted in 

 the number of cusps on the molar, a cusp, sometimes of 

 considerable size, but usually rudimentary, is developed at 

 the inner base of the main cusp, and in rare instances another, 

 much smal-ler, at the base of the cusp next behind the main 

 cusp. 



Female. The teeth are about one half smaller and less 

 obliquely inserted than in the male, and often vary from the 



male dentition in the reduc- 

 tion of the cusps, both in size 

 and number. The internal 

 accessory cusps, so often seen 

 in the male, seem to be uni- 

 formly absent. 



The teeth vary notably in 

 the development of cusps in 

 both sexes, as does also the 

 size of the teeth. Some fe- 

 males have nearly as heavy 



oo c<->mo -moloc c<~ 

 as SOme malCS, SO 



4-V>-rrviirrVi +"ho ixn'rlo -ro-nrro 



tnrougn tne wide range 

 of individual variation in 



this respect, one cannot be sure whether in skulls not marked 

 for sex a skull with rather weak dentition is a heavy-toothed 

 female or a light-toothed male. 1 



r Among the thirteen skulls here under consideration are three that differ strikingly 

 from the rest of the series. Two of them were received from Messrs. Barnum and 

 Bailey, and the other, at about the same date, from the Central Park Menagerie. These 

 three skulls, sexed as female, uniformly differ from the others in having only three 

 cusps instead of four on the lower molar. In one (No. 6366) there is a rudimentary 

 second posterior cusp, about as large as a small pin point. This skull agrees with the 

 only skull (No. 32) of known European origin available for examination, and I strongly 

 suspect that these three aberrant skulls are also European, and that the animals were 

 obtained through the well-known European dealer in menagerie specimens, Carl Hagen- 

 beck. If this conjecture is correct, the difference in the form of the last molar will 

 serve as a good distinguishing character between the females of the European and 

 North American Atlantic coast Harbor Seals. 



These same skulls differ from the other female skulls in lacking one cusp throughout 

 both the upper and lower premolar-molar series, the upper premolars lacking the second 

 posterior cusp, being bicuspid instead of tricuspid, while in the lower jaw there is a 

 corresponding reduction in the number of cusps. 



Fig. 4. Phoca 

 Am. Mus. No. 



oung adult' 

 y from coast of 



$. 



mtulina^ y 



14442, probabl 



Maine. Lower dentition, outside, inside, and 



crown views of teeth. Nat. size. 



