30 DR. J. E. GRAY ON THE SPECIES OF SEALS. (Jan. 26, 
In the younger specimen the edge of the palate has a slight pro- 
minence in the middle of each side ; but this is evidently an acci- 
dental deformity, as the prominences are not of the same size in the 
two sides. In the adult skull the two sides of the palate are evenly 
arched out. 
The lower jaw most resembles that of the restricted genus Phoca 
(of which P. darbata is the type) in being solid aud strong, and in 
the two sides being arched out, leaving a very wide oval space be- 
tween them, the front part of the space being continued by a tubercle 
on the inner edge of the front of the jaw, a short distance from the 
symphysis. 
In Phoca the tubercle on the inner side of the lower edge is short, 
rounded, blunt, and more or less rugose ; in the new Seal, Halicyon, 
it is a short-edged, elongated ridge. In Phoca the teeth are small, 
erect, and far apart ; and in Halicyon they are larger, closer together, 
and distinctly three or five lobed. 
In Halicyon the hinder edge of the ramus of the lower jaw is 
simple, with a distinct notch between it and the tubercular angle of 
the jaw. In Phoca the hinder edge of the ramus is inflected, form- 
ing a large half-oblong lobe, convex in front, and concave behind. 
(fig. 2). 
it ee interesting to observe that there is a representative genus 
on each side of the Arctic Pole; and this agrees with my previous 
experience—that each species of Seal has a limited, indeed I may say 
a very well-defined and very limited, geographical distribution. 
Though the species are very difficult to distinguish by their external 
characters, yet the skeleton, and especially the skull, affords well- 
marked and very definite characters. 
M. Lepechin described a Phoca oceanica (Act. Petrop. 1777, 259. 
t. 6 & 7), which has been considered the same as Pagophilus gren- 
landicus, as abundant on the ice around Nova Zembla. It would 
be curious to see the skull of a specimen from that locality, and 
thus discover which species extends itself so far north as those islands. 
Phoca oceanica, in its young and old state of fur, resembles Pago- 
philus grenlandicus ; but unfortunately we have only a very limited 
knowledge of the external appearance of this new Seal from Van- 
couver’s Island. 
The study of a large series of specimens of several species of Seals 
shows that the form of the lower jaw, though hitherto little attended 
to by zoologists, affords a very good character for the distinction of 
the species. 
In Pagophilus grenlandicus and Halicyon richardii the angle of 
the lower jaw is far back, and the hinder edge of the ramus ascends 
nearly perpendicularly, with a notch at the hinder end, as shown in 
fig. 6. In Phoca barbata the form of the lower jaw and ramus 
is nearly similar; but instead of a notch near the angle, the inner 
edge is produced inwards into a rounded lobe (fig. 2, and see Cat. 
Seals B.M. p. 27, f. 9). 
In Callocephalus vitulinus and C. (Pagomys) feetidus, on the con- 
trary, the angle of the lower jaw is more towards the front, and the 
