Van Diemen’s Land, now before me, which exceed six inches in length,
have the whole of their convex alveolar border beset with a band of
minute sharp conical rasp-like teeth; along the inner border of each
band there is a row of moderately long, slender, straight and very
acute teeth, with intervals of from four to six times their own diameter.
Their dentition resembles very closely that of the true Sauroid
Fishes.
The Garpike, (Belone vulgaris), has a row of large sharp conical
and recurved teeth, together with many small ones upon each of its
long intermaxillary and premandibular hones ; but the palatines and
hyoid are edentulous. There is a small patch of villiform teeth on
the vomer. The pharyngeals are paved with small tuberculate teeth.
The Mormyri have a simple row of small compressed and notched
teeth on each jaw : and villiform teeth on the tongue and vomer.
The Esox Lucius or~common Pike has an immense number of
teeth, all of which are conical, slender and sharp-pointed. They are
placed on the intermaxillary, premandibular, palatine, vomerine,
lingual, branchial and pharyngeal bones. The largest and most formidable
of these teeth are those situated in the lower jaw, and at the
anterior part of the palatines and vomer. The intermaxillary teeth are
small and slightly recurved, placed in a single or double alternate
row: the teeth at the anterior part of the lower jaw correspond
in size and arrangement with the intermaxillary ones; but the posterior
teeth are much longer and stouter, especially the first; they form
a single row, and are separated by wide intervals in which are situated
the successional teeth in different stages of development in a
recumbent position, directed inwards, and concealed by the gum.
The teeth of the palatines and vomer are arranged in numerous
close-set rows, the largest being placed at the anterior part of these
bones, and along the mesial edges of the palatines; those on the
vomer are so numerous, small, and close set, as to resemble the teeth
of a rasp. The mesial chain of hyoid bones supports four longitudinally
oblong patches of smaller rasp-like teeth. Similar teeth are
arranged along the inner surfaces of all the branchial arches; and the
four superior and two inferior pharyngeal bones are beset with somewhat
larger teeth of a similar conical, sharp pointed, recurved form.
ft is somewhat unusual in the present class, to find such an immense
number of teeth, so variously disposed over the parietes of the
mouth, yet presenting so uniform a shape; but all are here adapted
to pierce, seize, and retain a living prey, and are thus in perfect
conformity with the predaceous habits of the species. The fully
developed and functional teeth are attached by a confluence of their
bases with the surface of the jaw-bones, and not, as in Sphyrcena,
with the parietes of an alveolar cavity. The germs of the successional
teeth, also, instead of being developed in alveolar cavities,
complete their growth in the original seat of their formation, viz. the
vascular membrane or gum, which covers the dentigerous margins of
the jaws.
That the formation of a tooth is an act of conversion of the substance,
and not of cells upon a formative surface of the pulp, is
clearly illustrated in the Pike. The cone-shaped cap which the half-
developed tooth forms upon the remaining matrix can only be
removed by overcoming a certain resistance, and this resistance is
seen to be due to the processes of the pulp which extend into the
medullary canals of the tooth ; the broken ends of these processes give
an irregular surface to the exposed pulp, and their continuation into
the tooth may be seen by sawing the latter across. This connection
between the substance of the tooth and of the pulp is still better
demonstrated in a finely injected specimen: the mechanical relation
between the tooth and the pulp is then seen to be of precisely the
same kind as those between an ordinary osseous nucleus and the cartilaginous
matrix in which it is developed: it is in the course or direction
of development that the chief difference exists ; in the tooth
it is centripetal, in the bony epiphysis centrifugal; but the mode of
development is the same. In both cases a soft aind vascular model
and framework of the future hard part is prepared : in it the cells are
formed and the tubes are excavated according to the plan destined
for the future arrangement of the calcareous particles ; which arrangement
is not one of indiscriminate diffusion, but accords with the best
known mechanical principles, and is in prospective harmony with
the peculiar resistance which the calcified part is destined to overcome.
A vertical section of the matrix of a Pike’s tooth and the