two rows on each side, while the vomerine teeth are in four rows.
The teeth of the Mwrana Saga are small and numerous, and may be
said to be arranged ‘ en carde.’
In the skull of the Murana tigrina, figured in PI. 56, fig. 5 ,
of which the jaws are upwards of four inches in length, they are
armed with a pretty close-set row of strong conical teeth, b, with the
base extended transversely and firmly anchylosed to the alveolar
margin of the jaw, and the apex narrowed off to a pointed and somewhat
trenchant edge set lengthwise; on the outside of this row there
is an irregular series of small conical teeth, and in the inside a
broader stripe of small granular teeth. At the extremity of the
lower jaw two of the conical teeth are developed to a size much
exceeding the rest; they are surrounded by smaller conical teeth
which spread out like the prongs of a grappling-iron. These large
terminal teeth of the lower jaw are opposed to four similar large,
conical, sharp-pointed, divergent fangs on the -expanded anterior
extremity of the vomer. A longitudinal oval plate on the vomer
supports twelve large and strong conical teeth, anchylosed by transversely
extended bases ; these teeth are arranged in alternate pairs
m the middle of the group, but the rest form a single longitudinal
row, decreasing in size as they are placed anteriorly. The whole
dentition presents a most formidable armature for seizing and
lacerating a resisting prey. The vomerine teeth are indicated by
the letter a. In the great Oxyrhynchus the crowns of the teeth are
suh-compressed laterally and have an anterior and posterior dentated
edge.
LEPIDOSIREN.
64. At the extreme limit of the class of fishes, and connecting
that class with the reptiles, stands the very remarkable genus
of which the name is placed at the head of the present chapter, and
the dental system is figured in PI. 59. This consists of two small,
slender, conical, sharp-pointed and slightly recurved teeth, which
project downwards from the intermaxillary hone, and of strong
trenchant dental plates anchylosed with the alveolar border of the
upper and lower jaws, in each of which the plate is divided at the
middle or symphysial line so as to form two distinct lateral teeth.
The intermaxillary bone is represented by a single, horizontal,
triangular plate, the base of which is attached by ligamentous union
with the frontal and ascending process of the palatine bones,
upon which it enjoys a slight vertical movement; the rounded apex
forms the anterior extremity of the skull, and it is at the under
surface of this part that the two laniariform teeth are attached
by ligaments proceeding from their base, so as to admit of a yielding
motion in every direction for a small extent, hut most resisting
inflection outwards. Their office is to pierce and retain the nutritive
substance which is afterwards divided and comminuted by the strong
maxillary dental plates.
The upper pair of these plates is supported by the anterior
part of a strong arch of bone which combines the characters of
the superior maxillary, palatine and pterygoid bones : the superior
maxillary is represented by the external process which projects
outwards and backwards and terminates in a free point on
each side of the anterior part of the arch ; the palatine portion constitutes
the median and anterior part of the roof of the mouth ; the
pterygoid portion is indicated by its fulfilling the usual function of
an abutment extended between the palatine portion of the upper
jaw and the articular pedicle of the lower jaw : the upper dental plates
are confined to the first two parts of the arch and do not extend upon
the pterygoid portion; the lower dental plates are anchylosed to the
premandibular bone. Viewing the upper pair of plates as a single
tooth, it may be described as being indented at its outer surface by
five vertical angular notches, penetrating inwards through half the
breadth of the supporting bone, and dividing the plate into six
angular processes, which, from the direction and varying form and
breadth of the entering notches, radiate from the posterior part of
the median line or division of the tooth (PI. 59, fig. 3). The inferior
dental plate is similarly notched on its outer side, hut the proportions
of the angular indentations are such that they receive the
processes of the upper dental plate when the mouth is shut; thus
the median notch is wider than the two adjoining ones in the lower