This section is from the book "General Outline Of The Organization Of The Animal Kingdom, And Manual Of Comparative Anatomy", by Thomas Rymer Jones. Also available from Amazon: A General Outline of the Animal Kingdom and Manual of Comparative Anatomy.
"In the Cod-fish, Wolf-fish, and some other species, in proportion as the ossification of the tooth advances towards its base and along the connecting ligamentous substance, the subjacent portion of the jaw-bone receives a stimulus, and developes a process corresponding in size and form with the solidified base of the tooth. In this case the inequalities of the opposed surfaces of the tooth and maxillary dental process fit into each other, and for some time they are firmly attached together by a thin layer of ligamentous substance; but in general anchylosis takes place to a greater or less extent before the tooth is shed. The small anterior teeth of the Angler (Lophius) are thus attached to the jaw; but the large posterior ones remain always moveably connected by highly elastic, glistening ligaments, which pass from the inner side of the base of the tooth to the jaw-bone. These ligaments do not permit the tooth to be bent outwards beyond the vertical position when the hollow base of the tooth rests upon a circular ridge growing from the alveolar margin of the jaw; but the ligaments yield to pressure upon the tooth in the contrary direction, and its point may thus be directed towards the back of the mouth; the instant, however, that the pressure is remitted, the tooth flies back, as by the action of a spring, into its usual erect position.
The deglutition of the prey of this voracious fish is thus facilitated and its escape prevented.
"The broad and generally bifurcate osseous base of the teeth of Sharks is attached by ligaments to the ossified or semiossified crust of the cartilaginous jaws. The teeth of the Salarias and certain Mugiloids are simply attached to the gum. The small and closely-crowded teeth of the Rays are also connected by ligaments to the subjacent maxillary membrane. The broad tessellated teeth of the Eagle-Rays have their attached surface longitudinally grooved to afford them better holdfast; and the sides of the contiguous teeth are articulated together by true serrated or finely-undulating sutures, which mode of fixation of the dental apparatus is unique in the animal kingdom.
"If the engineer would study the model of a dome of unusual strength and so supported as to relieve from its pressure the floor of a vaulted chamber beneath, let him make a longitudinal section of one of the pharyngeal teeth of a Wrasse (Labrus.) The base of this tooth is slightly contracted, and is implanted in a shallow circular cavity, the rounded margin of which is adapted to a circular groove in the contracted part of the base; the margin of the tooth, which immediately transmits the pressure to the bone, is strengthened by an inwardly projecting convex ridge. The masonry of this internal buttress and of the dome itself is composed of hollow columns, every one of which is placed so as to transmit in the due direction the superincumbent pressure.
* Vide Yarrell's British Fishes. 8vo. 2 vols. 1 Owen, Odontography, p. 6.
"In another case, in which long and powerful piercing and lacerating teeth were evidently destined, from the strength of the jaws, to master the death-struggles of a resisting prey, we find the broad base of the tooth divided into a number of long and slender -processes, which are implanted like piles in the coarse osseous substance of the jaw; they diverge as they descend, and their extremities bend and subdivide like the roots of a tree, and are ultimately lost in the bony tissue. This mode of implantation, which I have detected in a large extinct Sauroid fish (Rhizodus), is perhaps the most complicated which has yet been observed in the animal kingdom".
(1773). For a full account of the growth and development of the teeth of Pishes, we must refer the reader to the same source from which we have extracted the preceding paragraphs; nevertheless the following is a brief abstract of Professor Owen's views upon this subject.
(1774). In all fishes, the first step in the formation of a tooth is the production of a simple papilla from the surface either of the soft external integument, as in the formation of the rostral teeth of the Saw-fish (Pristis), or of the mucous membrane of the mouth, as in the rest of the class. In these primitive papillae there can be very early distinguished a cavity containing fluid, and a dense membrane (membrana propria) surrounding the cavity (and itself covered by the thin buccal mucous membrane), which gradually becomes more and more attenuated as the papilla increases in size. The pulp-substance, or contents of the membra na propria, remains for some period in a fluid or semifluid condition; granules are ultimately developed in it, which at first float loosely, or in small aggregated groups, in the sanguineo-serous contents of the pulp. These granules soon attach themselves to the inner surface of the membrana propria, if they be not originally developed from that surface. The whole of the contents of the growing pulp becomes soon after condensed by the numerous additional granules which are rapidly developed in it after it has become permeated by the capillary vessels and nerves.
The particles become arranged into linear series or fibres - an appearance which is first apparent at the superficies of the pulp, to which the fibres are vertical. At this period ossification commences in the dense and smooth membrana propria of the pulp, and is thence continued centripetally in the course of the above-mentioned lines towards the base of the pulp. Lastly, around the capillaries of the pulp the granules become condensed into concentric layers, which then form the walls of minute tubes, visible on a microscopic examination of the substance of the tooth.
(1775). In some genera, as Balistes and Chrysophrys, an enamel-pulp is developed from the inner surface of the capsule which surrounds the bone-pulp, and by this organ the surface of the teeth of such fishes is coated with enamel in a manner to be described more at large hereafter.