680 DR. J. E. GRAY ON THE URSID&. [ Dec. 13, 
can be more distinct from each other than the species above named 
which have such similar skulls, showing that similar skulls do not 
always imply very nearly allied or doubtfully distinct species. 
The Bears‘may be arranged, by the size of the tubercular grinders, 
thus :— 
Very large, more than half as long again as the flesh-tooth. (The 
number gives the medium measurement of the flesh-tooth, in inches 
and twelfths.) 1! 4!', Ursus isabellinus. 1! 5!", U. cinereus. 
1! 4!"", U. grandis. 1" 3'", U. torquatus. 
Moderate above, half as long again as the flesh-tooth. Thalas- 
sarctos maritimus. 1! 2!', Ursus arctos. 1"', U. arboreus. 1", 
U. americanus. 1" 6'", Myrmarctos. 
Small, only rather larger than the flesh-tooth. Helarctos malay- 
anus, Melursus libycus. 
A. Sea-Bears. Soles of the feet covered with close-set hairs, with 
a few small bald pads. Head elongate; forehead scarcely 
raised above the line of the nose; cutting-teeth 6/6; lips 
slightly extensile ; nostrils moderate. 
1. THALASSARCTOS. 
Head elongate; ears rounded, hairy; forehead scarcely raised 
above the line of the nose. Neck elongate. Feet broad, large; front 
claws elongate, curved. Fur soft, short, dense. Skull elongate. 
_ The upper tubercular grinder elongate. The palate broad, concave, 
rather contracted behind, and then suddenly contracted behind the 
last tooth. The hinder nasal aperture elongate, narrow, the sides 
much longer than the front edge, which is arched ; the sides bent in 
towards the middle, contracting the aperture. 
Sea-Bears (Thalassarctos), Gray, Anu. of Philos. 1825. 
Thalassarctus, Gloger, 1842. 
Hab. Arctic Seas. 
THALASSARCTOS MARITIMUS. B.M. 
White or yellowish white. 
Ursus maritimus, Desm. Mamm. 165; Schreb. Saugeth. 513, 
t. 141*; Fischer, Syn. Mamm. 145; Baird, Mamm. N. A. t. 44 
(skull) ; Temm. Fauna Japon. 29 ; Schrenck, Amurland, i. 16. 
U. marinus, Pallas, Reis. ii. 691; P. Z. S. 1859, p. 102. 
U. polaris, Shaw, Mus. Lever. i. 7, t. 2. 
U. albus, Brisson, Régne Anim. 260. 
Thalarctos polaris, Gray, Ann. Philos. 1825, p. 62. 
Thalassarctos maritimus, Gray, Cat. Mamm. B. M. 73; Bonap. 
Cat. Mamm. Eur, 11. 
Ours blane (U. maritimus), De Blainv. Ostéogr. t. 1 (skeleton @ ), 
t.4 (bones), t. 5 (skull 2). 
