the jaw. Retzius(l) has disproved at some length this supposed
peculiarity in the mode of attachment of the teeth to the jaw;
he observes that, ‘ at a short distance from the line of attachment
of the teeth, there is a margin resembling an alveolar edge
(it is clearly shown in PI. 60, fig. 1, below the tuberculate teeth in
the right premandibular bone) : ‘ the portion of the jaw bone intervening
between this margin and the teeth consists of a peculiar porous osseous
substance, (2) and has on both sides small furrows corresponding with
the interstices of the teeth, and giving to the basilar substance the
appearance of being divided into as many processes as there are
teeth this appearance is still more increased by the small openings,
one at the end of each vertical furrow nearest the quasi-alveolar edge,
which openings lead, according to Retzius, to cavities containing the
germs of the successional teeth.
The dentigerous or alveolar processes of the jaw-bone are still
more distinct at the anterior border of the premandibulars and
intermaxillary bones, but these are not more developed in the wolffish
than they are in the angler, the cod and other fishes with anchy-
losed teeth. The line of union of the tooth is situated at the summit
of these processes ; it is at this line that they are commonly detached;
and not by a separation of the alveolar process from the rest of the jaw,
either by interstitial absorption, analogous to that which causes
the shedding of the antler of the deer, or by any other natural
process.
In reference to the structure of the teeth of the wolf-fish Mr.
André rightly observes “ that they are formed of a hard bony matter
not covered with enamel as in some animals,” and Retzius confirms
this statement in reference to the fully developed and fixed teeth ;
but he states that in the germs of the teeth contained in the alveoli
of reserve there is a small portion of enamel, which in the conical
teeth constituted the summit, and in the tubercular ones formed a
white elevation, one third of a line in breadth, upon the centre of the
flattened grinding surface. “ It is no wonder,” says Retzius, “ that a
fish which uses its teeth for bruising thick shells, as those of whelks,
(1) Müller’s Archiv. 1837, p. 529.
(2) I find it however not to differ in texture from the remaining peripheral dense part of
the jaw-bone, as shown in PI. 60, fig. 2.
BLENNIOIDS. GADOIDS. 161
and cockles, lobsters, sea-urchins, &c., should soon wear off these
small enamel points, which cannot therefore have much functional
importance. These transitory summits, which are composed in
reality of a fine tubular dentine, were supposed by Cuvier to be the
true teeth, and to be peculiar to the young wolf-fish : he gives a
figure of one of them in PL 32, fig. 6, a, of the Leçons d’Anatomie
Comparée, vol. v, 1805.
The calcification of the dentinal pulp proceeds in nearly parallel
lines from the summit to the base of the tooth ; it is this peculiarity
in the wolf-fish that occasions the solidity of the teeth, and the
general straight course of the medullary tubes ; most of these run
parallel to each other and to the axis of the tooth ; but the tubes
nearest the sides of the tooth slightly diverge towards that surface.
Tracing the medullary canals from the basis of the tooth, they
divide dichotomously into finer and parallel branches, which form
numerous reticular anastomoses together and terminate in fine
loops at the periphery of the tooth. The medullary canals are
occupied by processes of a vascular pulp ; they were seen and
described by both Cuvier and Von Born, who conceived them to
be the channels of the nutrient vessels and nerves, and they were
rightly compared by the latter anatomist to the similarly conspicuous
tubes which traverse the teeth of the Orycterope ; but the structure
of both teeth is much more complicated than that of the horn of the
rhinoceros, or of the baleen of the whale. The minuter or calcigerous
tubes which traverse the firm substance occupying the interspaces of
the medullary canals were not perceived in either case, by the above-
cited anatomists ; they are extremely minute in the Anarrhichas, and
do not form by their parallel and straight course a distinct enamellike
outer layer, as in the pike, except at the apex of the recently
formed teeth, but are confined to the fine and inextricable reticulate
anastomoses at the periphery of the tooth as well as in the interspaces
of the medullary canals.
GADOIDS.
62. The dental system maintains a greater uniformity in the
Cod-tribe than in most of the other natural families of the class of
M