THE CRESTED SEAL 733 



w dd 11' S 1 Weddell's seal (Leptonychotfs weddelli} is (-another Antarctic 

 species, distinguished by the teeth having simple conical and some- 

 what compressed crowns, without additional fore-and-aft cusps. It was originally 

 obtained from the Southern Orkneys, but has also been obtained from Patagonia 

 and the Antarctic pack ice. The general color is very similar to that of the leopard- 

 seal, being pale grayish above, spotted with yellowish white on the back, and 

 yellowish beneath. The jaw is weaker and the sockets of the eyes are larger than 

 in the leopard-seal. 



The last of these four southern species is Ross's seal (Ommatophoca 

 Ross's Seal 



rossi ) , long known by two skulls and a single skin obtained from the 



Antarctic pack ice during the voyage of the Erebus and Terror in the years 

 1839-1843, and appropriately named after the commander of that expedition. The 

 fur is rough and coarse, with general greenish-yellow color, .marked with oblique 

 yellow stripes on the sides of the body and paler on the under parts. There are no 

 claws on the hind-feet, and but very small ones in front. The skull is character- 

 ized by the immense capacity of the sockets of the eyes, and also by the small size 

 of the teeth. The cheek-teeth have very small fore-and-aft cusps. 



One of the two known skulls of this seal is peculiar in that, while on one side 

 the first upper cheek-tooth and both the corresponding lower teeth are imperfectly 

 divided by a vertical groove, on the opposite side of the upper jaw the place of this 

 tooth is taken by two complete simple teeth. Hence, it is obvious that we have here 

 a case where an originally single tooth divides into two distinct but simpler teeth. 

 This may not at first sight seem a fact of much importance; but in reality it serves 

 to show how the numerous simple teeth characteristic of the toothed whales may 

 have been derived by the splitting up of teeth originally composed of three distinct 

 cusps like those of the leopard-seal; each cusp of such a tooth forming, as we shall 

 see, a distinct tooth in the whales. 



THE CRESTED SEAI, 

 Genus Cystophora 



The remarkable-looking animal represented in the illustration on the next page, 

 and commonly known as the crested, hooded, or bladder-seal (Cystophora cristata), 

 is at once distinguished from all the other members of the family by the casque-like 

 prominence crowning the fore part of the head. This seal, together with the 

 under-mentioned elephant-seal, differs from all the species yet noticed in having but 

 thirty teeth, owing to the reduction of the incisors to two pairs in the upper, and 

 to one pair in the lower jaw. In both the cheek-teeth are small and simple, with, 

 in general, but a single root each; and in the males of both the nose is furnished 

 with an appendage which can be inflated at will. Moreover, the first and fifth toes 

 of the hind-feet are considerably longer than the three middle ones, and are fur- 

 nished with long lobes projecting in advance of the rudimentary claws, or the posi- 

 tion which these should occupy. 



