SPER3I-WHALE. 
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are the Toothed Whales or Odontoceti, and the Baleen Whales 
or Mystacoceti. 
Suborder I. Odontoceti, or Delphinoidea. 
Among other important anatomical characters, these have no 
baleen or whalebone, but always possess teeth, which are generally 
numerous^ but sometimes few and quite rudimentary in size and 
function. The upper portion of the skull is more or less asym- 
metrical. The olfactory organ is absent. The two branches of the 
mandible or lower jaw come in contact in front by a flat surface of 
variable length, but always constituting a true symphysis. Several 
pairs of ribs are connected with the elongated sternum by means 
of costal cartilages, which are often ossified. The external respira- 
tory aperture or blowhole is single, the two nostrils uniting before 
they reach the surface, and usually in the form of a transverse 
crescentic valvular aperture, situated on the top of the head. 
Family Physeterid^. 
The members of this family are united by several common 
characters of the skull and vertebral column, by never having 
functional teeth in the upper jaw, and by their costal cartilages 
never becoming ossified. 
The most interesting member of this family is the great Sperm- 
Whale or Cachalot {Physeter macrocephalus) , of which the skeleton 
of one which was cast ashore on the rocky coast of Caithness, near 
Thurso, in June 1863, is mounted in the central hall of the Museum. 
It is 50 feet long (measured in a straight line), which is about the 
average length of a full-grown specimen of this animal, and appears 
never to be greatly exceeded, notwithstanding the exaggerated state- 
ments of their attaining 80 or 100 feet in length. It feeds chiefly 
on cephalopods and fish, and is one of the most extensively distri- 
buted of Cetaceans, being met with, usually in herds or schools,'’-’ in 
almost all tropical or subtropical seas, but not occurring, except 
accidentally, in the Polar Regions. Those that appear occasionally 
on the British coasts are solitary stragglers, usually, if not always, 
old males, as in the present instance. The oil contained in the great 
cavity above the skull, when refined, yields spermaceti,^-’ so much 
used in the manufacture of candles and of ointments, and the thick 
