arranged, in the young specimens, in four rows, and all present the
hemispherical form. When the individuals have attained seven or
eight inches in length, the third row presents three teeth of conspicuously
larger size. In a Gilt-head of eleven inches in length,
the molar teeth of the upper jaw are in five rows, and the fourth
row presents three teeth larger than the rest, of a sub-elliptic form,
with the long diameter transverse; the large elliptic molars of the
adult, of which the long diameter is in the axis of the body, is now
formed, hut is still concealed in the substance of the jaw. When it
has come into place, the mature dentition may he said to be complete.
The base of the fully formed teeth in use is anchylosed, but
in a slighter degree than usual, to a thin osseous lamella, which forms
the floor of a shallow depression or alveolus in which the base is
lodged. The flat lamella is perforated by numerous foramina, and
the sides of the alveolar depression are grooved with numerous
radiating lines.
The texture of both the pointed and obtuse teeth is extremely
densejj it consists of a body of hard white dentine, and a coat
of organized enamel, analogous , to that of the incisors of the file-
fish. The crowns of the rounded molars of the gilt-head hardly
suffer the saw to make an impression upon them. Their calcigerous
tubes are very numerous and extremely minute, and cross each other
towards the periphery of the tooth at acute angles, as in the molars
of Lepidotus. The microscopic structure of the anterior pointed
teeth resembles that of the incisors of the Sargus, which will be
described in the next section.
38. Sargus.-—Fishes which present so close a correspondence in
their general conformation and zoological characters as to be included
by Linnaeus in the same genus, and by Cuvier in the same natural
family, may, nevertheless, differ widely in their habits and be
nourished by the most opposite kinds of food, and these peculiarities
will be associated with modifications of the digestive system, and
especially of the teeth. Of this we have a striking example in the
Bream-tribe. In the Dentex (the Sparus dentex of Linnaeus), the
dentition was of a predatory and destructive character, all the teeth
being formed to seize, and pierce, and lacerate. In the Chrysophrys
(Sparus aurata, &c. Linn.), the laniary type was limited to the anterior
teeth, while those which corresponded with the lateral teeth of the
Dentex had exchanged their piercing for a crushing form, and the
small miliary denticles which are scattered over the inner side of the
alveolar border in the Dentex argyrozona, had risen, as it were, from
their rudimental condition, begun to assume a functional character,
and to be counted as a second and third row of molar teeth.
In the sub-genus, of which the dentition is now to be described,
the transition from the carnivorous to the herbivorous type is effected
by simply modifying the form of the large anterior teeth, and converting
them from piercing to cutting instruments.
Their crowns, instead of tapering to a point, are widened
laterally, compressed from before backwards, and truncated at the
extremity ; they are flat or slightly convex on the outer surface, and
concave on the opposite side, and in the larger species of Sargus
closely resemble, in size and shape, the incisors of the human subject.
This resemblance has caught the attention of most ichthyologists who
have had occasion to describe any of the species of the present genus.
Salviani characterises his Sargo or Sargone, among other marks, by
the “ dentibus latis, humanis sim ilib u sKlein and Cuvier extend the
same comparison to the “ Sargues ” in general; and had Scheuchzer
founded his supposed discovery of the Homo diluvii testis on a fossil
incisor of the present genus, instead of the skeleton of a gigantic salamander,
the mistake would have been more venial, and might not so
soon have been rectified.
“ Tout-k-fait semblables aux incisives deThomme,”(l) is, however,
a somewhat exaggerated expression of this relation, even in the
Sargus Rondeletii. The fang of the fully formed, but unattached tooth,
(such as those of which the crowns are figured(2) protruding through
the apertures exterior to the base of the incisors in place), grows
wider to its free extremity instead of contracting; while, in the
incisors in use, this fang is anchylosed to the alveolar margin of the
jaw, as in fishes generally. The antero-posterior diameter of the fang
is also greater in proportion to its lateral diameter than in the human
incisor.
(I) Cuy. and Val. Hist. Nat. des-Poissons, vi, p. 16. (2) PI. 42, fig. 2.