Sperm- Whales. 25 
Physodon, Eucetus, or Dinoziphius), Thalassocetus, Physeterula, 
Prophyseter, Placoziphius, and Hypocetus (Diaphorocetus), all of 
which have teeth in both jaws. The last of these, which is 
common to the Miocene of Nortb and South America, seems 
to be the ancestor of Physeter or Kogia, probably of the former. 
The Sperm-Whale itself is represented in the gallery by the 
skeleton (upon which a half-model is built) of an old male, washed 
ashore in Sandside Bay, near Thurso, Caithness, in July, 1863. 
The specimen measured fifty-five feet in length, and was presented 
by Captain D. Macdonald, R.E. 
On the eastern wall of the room are suspended four lower 
jaws of young Sperm-Whales. Two of these have been injured 
in life, probably through collisions, and their extremities have 
consequently grown in a curve. 
In one of the table-cases at the north end of the room is 
exhibited a considerable series of detached teeth of the Sperm- 
Whale. As already mentioned, and as shown in the complete 
skeleton, functional teeth are developed only in the lower jaw of 
the Sperm-Whale ; these vary in number from 20 to 25 pairs, the 
largest being situated in the middle of the series. They have no 
enamel, and consist externally of the substance known as cement, 
and internally of dentine, together with nodules of a harder 
variety of the same substance termed vaso-dentine. The pulp- 
cavity remains open throughout life in these teeth. On one of 
the smaller specimens has been incised a sketch of a Sperm- 
Whale hunt, in which the truncated front of the head characteristic 
of old bulls is distinctly shown. 
Tn another case are exhibited a number of fossilised teeth of 
extinct Sperm-Whales. The “Crag,” or Pliocene formation, of 
East Anglia and late Tertiary deposits in other parts of the world 
yield teeth of various extinct Cetaceans more or less nearly allied 
to the Sperm-Whale. They have been referred to a number of 
genera, such as Balznodon, Scaldicetus, Eucetus, and Physodon, 
but these appear to be for the most part inseparable. These 
extinct Sperm-Whales are distinguished by the presence of teeth 
in the upper as well as in the lower jaw (fig. 9). The teeth differ 
from those of the Sperm-Whale in having a cap of enamel on the 
summit; while some of them are characterised by their nearly 
circular cross-section, and by the swollen size of the aperture of 
the central pulp-cavity. 
Ambergris (literally “ grey amber’) is a concretion formed in 
