form the greater part of the superior margin of the mouth, and together
with the small intermaxillaries,. and the slender premandibulars,
are armed with small, hut very sharp-pointed teeth : the vomer and
the long palatines support similar, but smaller teeth, arranged in a
single series: the pterygoid, hyoid, branchial and pharyngeal teeth
are villiform.
The Sudis gigas, the largest not only of the Clupeoid family hut
of all fresh-water fishes, is not less remarkable for the number of the
teeth, than for the number of bones over which they are distributed,
the dental system is represented in figs. 4. 5 & 6, Pl. 48. Not only do
the intermaxillary (a) the superior maxillary bones (6), the premandibu-
lars (ƒ), the palatine (c), the vomerine (e), the lingual (fig. 6), the branchial
and pharyngeal bones support teeth, as in many Clupeoid and Sal-
monoid fishes, but the internal pterygoid bones (d d) and the basisphe-
noid (ƒ) have their under surfaces beset with innumerable denticles.
The maxillary teeth are implanted in a continuous alveolar groove
of the bones which circumscribe the aperture of the mouth, and are
attached to the groove by a ligamentous union. These teeth are
conical, much compressed, with an obtuse apex, near to which the
pulp-cavity extends. The other dentigerous bones are beset with
numerous, close-set, minute, short, cylindrical teeth, with convex,
graniform summits. The surface of the tongue is formed by the hard
granulated dentigerous surface of the median ossicles of the os hyoides,
which are broad and flat; the anterior of these ossicles is much
elongated; in a Sudis gigas, seven feet in length, it measures six
inches in length and two inches in breadth. (1)
In the genus Erythrinus, the intermaxillary, maxillary and pre-
mandihular bones are formidably armed with conical sharp-pointed
teeth, alternately large and small; the palatine, pterygoid, hyoid,
and pharyngeal bones are beset with minute villiform teeth. The
rapacity of these clupeoid fishes corresponds with the power of their
maxillary weapons. In the stomach of a specimen of the ErythTinus
macrodon, brought from Brasil in spirits, and dissected by M. Agassiz,
he found another species of the same genus, more than a third part of
the length of the fish by which it had been swallowed. (2)
(1) It is used as a rasp for culinary purposes by the Indians of thé Brazils.
(2) Spix, Pisces Brasilienses, p. 41.
In the genus Osteoglossum, the dental system of which is shown
in the large middle figure of Plate 48, the intermaxillary bones (a)
form only a small portion of the median and superior margin of the
mouth; the remainder is completed by the superior maxillaries (b b),
which, with the premandibular bones in the lower jaw, are armed
with a single series of equal, small, conical and sharp-pointed teeth :
near the lax symphysis of the lower jaw, there is a second series of
similarly shaped retro verted teeth. The vomer and anterior part of the
palatine hones are beset with small acute teeth ; the posterior part
of the palatines and the entire lower surface of the pterygoids are
covered with villiform denticles, but there is a row of longer sharp-
pointed teeth at the inner border of each pterygoid bone. The broad,
long, and flat lingual bone, (e), is covered with minute close-set pointed
teeth, converting the upper surface of the tongue, into a hard honey
rasp, whence the name of the genus. The branchial arches and the
inferior pharyngeals support villiform teeth.
The genus Glossodus affords additional examples of those fishes
in which the body of the os hyoides is provided with tubercular
teeth which are opposed to similar instruments for crushing the
alimentary substances, attached to the body of the sphenoid and
to the pterygoid bones. The maxillary, vomerine, palatine, branchial
and pharyngeal bones, both superior and inferior, are beset with
minute villiform teeth.
In the three preceding genera of South American tropical fresh-water
fishes the broad, long and flat dentigerous plate, into which one of the
median hyoid ossicles is developed, forms a striking characteristic of
their dental system, and I shall here describe similar dentigerous
plates, found fossil, in the eocene formation, called the ‘ London Clay,’
at the Isle of Sheppey.(l)
As these remains have hitherto been met with detached and unconnected
with the other bones of the skull, and exhibit little more
than the dentigerous covering, it cannot be unequivocally determined
whether they are the dentigerous armature of a broad lower pharyn-
(1) Specimens of these are preserved in the well known collection of Sheppey. Fossils of
J. S. Bowerbank, Esq., F.G.S., whose liberality in permitting their description on this, as on
many other occasions, I have gratefully to acknowledge.