slender, sharp, conical, slightly incurved crowns, and diminish
in size to the two extremes of each dental series; the acute apices
are longer preserved than in the foregoing species. In PI. 88, fig. 2,
the teeth of the upper jaw of an immature Dolphin are exposed
in situ, and both the extent of their implanted base and that of
their pulp-cavity is displayed.
The teeth of the common Porpoise fPhocosna vulgaris), are
arranged in equal number on each side of both upper and lower
jaws, and are from 80 to 92 in number; the crown is slightly
expanded and compressed, and the fully-formed fang is recurved
and enlarged at its extremity.
The gangetic Dolphin ('Platanista gangeticaj differs from the
rest of the Delphinidce scarcely less in the form of its teeth than
in that of the jaws; both the upper and lower maxillary bones
are much elongated and compressed; the symphysis of the lower
jaw is co-extensive with the long dental series, and the teeth rise
so close to it that those of one side touch the others by their
bases, except at the posterior part of the jaw; the lateral series
of teeth are similarly approximated in the upper jaw at the median
line of union, which line is compelled by the alternate position of
the teeth, to take a wTavy course.
There are thirty teeth on each side of the upper jaw, and thirty-
two on each side of the lower jaw (l); in the young animal they are all
slender, compressed, straight, and sharp-pointed, the anterior being
longer than the posterior ones, and recurved. Contrary to the
rule in ordinary Dolphins, the anterior teeth retain their prehensile
structure, while the posterior ones soon have their summits worn
down to their broad bases. The most remarkable change that
occurs in the progress of growth is the antero-posterior expansion
as well as elongation of the implanted base of the tooth, which
likewise has its outer surface augmented by longitudinal folds
or indentations, analogous to, hut weaker than those in the base
of the teeth of Sauroid fishes. Sometimes the posterior tooth of the
Platanista has the base divided into two short fangs,—the sole
example of such a structure which I have met with in the existing
(2) pi. 90, fig. 7.
Carnivorous Cetacea. Sir E. Home in a Paper published in the
Philosophical Transactions(1) descriptive of the teeth of the Platanista,
('Delphinus gangeticus), says of their structure that “ the perfect
tooth has a tolerably sharp enamelled point, and the lower portion
has no enamel.” This part which forms the implanted base, is
thickly coated by cement; and the pulp-cavity is obliterated. The
summits of the teeth are worn or broken off rather suddenly,
beyond the tenth in the upper, and beyond the eleventh tooth
in the lower jaw ; these anterior teeth are worn by mutual attrition,
the upper ones on the posterior and inner part of the crown, the
lower ones on the anterior and outer sides.
143. Physeter.—The outward and visible dentition of the great
Sperm-whale or Cachalot (Physeter macrocephalusj is confined to
the lower jaw, the symphysis of which is co-extensive with four
fifths of the entire dental series. This series in the male Cachalot
consists in each ramus of twenty-seven subincurved conical, or
ovoid teeth, according to their state of development and usage ;
the smallest teeth are at the two extremes of the series (PI. 89,
fig. 1). In the young Cachalot they are conical and pointed; usage
soon renders them obtuse, whilst progressive growth expands and
elongates the base into a fang, which then contracts, and is finally
solidified and terminated obtusely.
In the lower jaw of a female Cachalot in Dr. Buckland’s
Museum, the first and the last teeth have the pulp-cavity solidified;
in the rest it is widely open, and the lower margin of the tooth
forming the base of the conical cavity is very sharp. From the
last or hindmost, the teeth gradually increase to the tenth, then
continue of equal size to the nineteenth, and again gradually diminish
to the twenty-second, counting forwards, that being the total number
in each ramus. My friend Mr. Broderip possesses a tooth of a
male Physeter, with the base open and uncontracted, which measures
nine inches and a half in length and nine inches in circumference and
weighs three pounds.(2)
The teeth are separated by intervals as broad as themselves. In
(1) 1818, p. 417.
(2) An ingenious whale-fisher has ca rved in his leisure moments the chief incidents of his
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