Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 5, BUR-CHI

342
CETOLOGY.
Anatomy
and
The form of the head is commonly a cone or in-
dined plane. The Ipermaceti whale is an exception
, 10 to this, in which it terminates in a blunt lurface. The
head is larger in proportion to the body than in qua-
Formof thedrupeds, and fwells out laterally at the articulation of
iicad ; the lower jaw. This feems to be of advantage to the
animal in catching its prey, as there is no motion of
the head on the body.
;I03 Behind the pe&oral fins, at the infertion of which
of the bo y- the circumference is greateif, the body gradually di-
minifties to the fpreading of the tail. The body is bat¬
tened laterally } and it would appear that the back is
iharper than the belly, which is nearly fiat.
The progreffive motion of the animal is performed by
the tail, which moves the broad termination or lobes,
operating in the fame manner as an oar in fculling a
boat. And for the purpofe of preventing any obitruc-
tion in moving through the water, it may be obferved
that all the external parts of the clafs mammalia, that
live on land, are either entirely wanting, or are con¬
cealed under the Ikin in cetaceous fifties.
104
Power of
the tail.
Sect. I. Of the Bones.
r05
The (kele-
ton gives
no idea of
the general
form.
106
Bones of the
I’.ead ;
107
of the neck
and back;
10,
The bones alone, Mr Hunter obferves, when proper¬
ly united into the ikeleton, in many animals give the
general Ihape and character. But this is not fo de¬
cidedly the cafe in this order of animals. In them the
head is immenfely large, the neck Imall, there are few
ribs, in many a very ftiort iternum, and no pelvis, with
a long fpine terminating in a point, fo that thefe bones
being merely joined together do not alford any idea of
the regular Ihape of the animal. The different parts of
the Ikeleton are fo enclofed, and the projefting (paces
between the parts fo filled up, that they are altogether
concealed, and give to the animal externally an uniform
and elegant form.
The great fize of the bones of the head leave but
a fmall cavity for the brain. In the fpermaceti whale
it is not eafy to difeover where the cavity of the ikull
lies. This is alfo the cafe with the large whalebone
and bottle-nofe whale. In the porpoife, the Ikull con-
ftitutes the principal part of the head : for the brain
is found to be co'nfiderably larger in proportion to the
fize of the animal. The bones of one genus differ
very much from thofe of another. In the fpermaceti
and bottle-nofe whales, the grampus and the porpoife,
the lower jaws, efpecially at the pofterior ends, refera¬
ble each other 5 but in others it is very different. The
number of particular bones is alfo obferved to vary very
much.
Vertebra.—The piked whale has feven vertebrae in
the neck, 12 in the back, and 27 to the tail. 1 his
makes the whole number 46. In the porpoife the cer¬
vical vertebrae are feren in number. There is one
common to the neck and back, 14 proper to the back,
and 30 to the tail, making in whole 51. The cervi¬
cal vertebrae of a bottle-nofe whale, were the fame in
number as thofe of the porpoife. There were 17 in the
back and 37 in the tail, which make the whole num¬
ber 60. Four of the vertebrae of the neck in the por¬
poife are anchylofed, or have grown together. The
atlas in every one of this order of animals that has been
examined is the thickeft of the vertebrae. It feems to
Chap/1!
be compofed of two. There is no articulation between Anatom
the firit and lecond vertebrae of the neck to admit of an(l
rotatory motion. The vertebrae of the neck are very ' a}ll°^
thin, fo that the diftance between the head and thoulders
is as ftiort as poftible. ic8
Sternum or Breafbone.—This is very flat in the piked of die
whale, and confifts of a Angle very ihort bone. The^rea^'
breaftbone of the porpoife is confiderably longer j it is
compofed of three bones, which are of iome length in
the fmall bottle-nofe whale. The firft rib of the piked
whale, and the three firit of the porpoife are articulated
to the iternum.
Bibs.—T he fmall bottle-nofe whale, diffedted by Mr Ribs
Hunter, had 18 ribs on each fide j and the porpoife had
16. f ifteen ribs have been reckoned in the Ikeleton of
the dolphin. A large whalebone whale had 15 ribs on
each fide, which were 21 feet long and 18 inches in
circumference. The fpermaceti whales which were
thrown aftiore on the coaft of Brittany in France, had
only 8 ribs on each fide. They were 5 feet long and
6 inches in circumference. _ no
The ends of the ribs that have two articulations, inarticulats
the whole of this tribe, Mr Hunter obferves, are arti-
culated with the body of the vertebrae above, and with
the tranfverfe proeefles belew, by the angles, io that
there is one vertebra common to the neck and back.
In the large whalebone whale the firft rib is bifurcated,
and confequently is articulated with two vertebrae. ItI
FeBoral or lateral fins.—Thefe are analogous, and Pc&orai
fomewhat fimilar in conftrudlion to the anterior ex-^nsfimH
tremities of quadrupeds. They are compofed of a
fcapula or fiioulder-blade, os humeri, ulna, radius, car- qUa£irupc
pus, and metacarpus, which laft may include the fin¬
gers, the number of bones being iuch as may be
reckoned fingers, although they are included in one
general covering. The number of bones in each is
different, the fore-finger has five, the middle and ring-
finger has feven, and "the little finger has four. Theie
bones are not articulated by capfular ligaments as in
quadrupeds, but by intermediate cartilages attached to
each bone. Thefe cartilages are nearly equal in length
to one-half of the bone. This conftruajon gives
firmnefs and a confiderable degree of pliability to the
whole. . 11
Teeth.—Of this tribe of animals fome have teeth in Teeth
both jaws, fome have them only in one, while there
are others which have none at all. The teeth cannot
be divided into claffes as in quadrupeds. They are all
pointed teeth, and are pretty much fimilar in form and
fize. Each tooth is a double cone, one part of which
is faftened in the jawr, and the other projedfs above the
gum. In fome, indeed, the fang is flattened and tain
at the extremity } and in others it is curved.
The formation of the teeth, and their progrefs after
wards, feems to be different from that of quadrupeds:
For they feem to form in the gum, fo that they muft l°™e<1u5, !
either extend and fink into the jaw, or the alveoli muft
rife to enclofe them. Mr Hunter thinks this laft the
moft probable, fince the depth of the jaw is increafed,
fo that the teeth feem to fink deeper and deeper in it.
This mode of formation is obferved in jaws that are
not fully grown ; for, as happens in other animals, the
teeth increafe in number as the jaw lengthens.
It does not appear that they flied their teeth, °r ^
113
have
2