SPERM-WHALE. 
Ill 
covering of blubber which everywhere envelops the body produces 
the valuable sperm-oil of commerce ; hence this animal has long 
been the subject of a regular chase^ by which its numbers have been 
greatly diminished. The substance called ambergris,” largely 
used in perfumery, is a concretion formed in the intestines of the 
Sperm-Whale, and is found floating on the surface of the seas 
which they inhabit. Its genuineness is attested by the presence of 
fragments of the horny beaks of the cephalopods on which the 
Whales feed. 
A large skull of a Sperm-Whale, which has been in the Museum 
since the end of the last century, is placed in the anteroom through 
which the Cetacean Gallery is entered, and the remarkable form 
of the lower jaw, with its numerous stout conical teeth, is shown 
in a specimen suspended to the ceiling near the entrance of the 
Gallery. 
Nearly allied to the Sperm-Whale, but of very much smaller 
size, is Kogia hreviceps^ of which but few specimens have hitherto 
been met with. The skeleton exhibited is from the neighbour- 
hood of Sydney. 
The Ziphioid Whales, or ZiphiiruB, a section of the Physeteridce, 
constitute a very interesting group, of which most of the different 
forms are represented in the collection by skeletons and skulls. 
They resemble the Sperm-Whale and Kogia in having no teeth in 
the upper jaw (or if present they are in an exceedingly rudimen- 
tary state, and attached only to the gum of the mouth, not fixed 
in the bone), but differ, inasmuch as in the lower jaw the teeth, 
instead of being numerous, are reduced to one, or very rarely two, 
pairs. These are situated either quite at the front extremity of the 
jaw, as in Ziphius and Hyperoodon, or near the middle, as in Me- 
soplodon. In one of the last-named genus {M. layardi)^ from the 
South Seas, these teeth are much elongated and flattened, and in 
old animals (as in the skull exhibited in the Table-Case) curve 
round and meet over the upper jaw, so as almost to prevent the 
mouth from opening. This remarkable disposition of the teeth has 
been found in so many individuals that it must be looked upon as 
normal, and not, as at first thought, an accidental peculiarity, 
though it is difficult to understand how it is consistent with the 
animal obtaining its food. 
The best known animal of this group found in the British seas 
