PISCES. 



977 



Fjg.511. 



Seeing, therefore, that the teeth of Fishes are 

 derivations from pulps formed by the mucous 

 lining of the mouth, it can be a matter of small 

 astonishment to find that they can be developed 

 in any part of the oral cavity where the 

 necessities of a given species may require 

 their presence, without relation to the jaws, 

 with which alone they are connected in the 

 highest races of Vertebrata and in the human 

 subject. 



Accordingly in the class under consideration 

 teeth are found attached to any or all of the 

 following parts of the mouth and of the pha- 

 rynx, viz. to the superior and inferior maxillae, 

 to the intermaxillary bones, to the palate bones, 

 to the vomer, to the tongue, to the branchial 

 arches, and to the superior and inferior pharyn- 

 geal bones. The ichthyologist is therefore com- 

 pelled to designate the different parts of the 

 dental system according to the bones or other 

 structures whereon they are situated, and distin- 

 guishes intermaxillary teeth, maxillary teeth, 

 mandibular teeth, vomerian teeth, palatine teeth, 

 pterygoid teeth, lingual teeth, branchial teeth, 

 superior pharyngeal teeth, and inferior pha- 

 ryngeal teeth, all of which may sometimes be 

 coexistent, rendering the teeth of Fishes prodi- 

 giously numerous. As relates to their form 

 the dental organs offer a far greater number of 

 varieties than those of other vertebrate animals. 

 Sometimes they are so minute as only to be 

 perceptible by the rough or scabrous surface 

 which the parts of the mouth to which they are 

 attached present. If of larger size, they pre- 

 sent the appearance of a file or rasp (dents en 

 rape), or they may have the shape of small 

 cones or hooks thickly scattered over the pa- 

 rietes of the mouth. Sometimes they are so 

 fine and slender as to resemble the pile of 

 velvet (dents en velours), or elongated, having 

 the appearance of fine bristles. In Citharinu 

 these bristle-shaped teeth are bifurcated to- 

 wards their free extremities, or they may termi- 

 nate in three diverging points, as in the anterior 

 teeth of the genus Plata.v. Or the elongated 

 cone may be compressed into a slender tren- 

 chant plate, and this may be pointed, recurved, 

 or even barbed like a fish-hook, as is the case 

 in Trichiurus and some other Scomberoid 

 Fishes ; or it may be bent upon itself like a 



VOL. III. 



tenter hook, as in Pemeleptertts and Go- 



nioduntes. Sometimes the dental cones 

 present a thickened base, giving them the 

 appearance of the laniary teeth of carni- 

 vorous quadrupeds, as is the case with 

 the large teeth of the Pike ; or they may 

 be flattened into broad plates of hemi- 

 spherical or other shapes, constituting a 

 crushing apparatus adapted to bruise the 

 food. 



A thin lamella, slightly concave like a 

 finger nail, is the singular form of the 

 tooth of an extinct species of cartilaginous 

 fish named by Professor Owen Petulo- 

 dux* Sometimes each tooth presents a 

 flattened incisor crown deeply notched in 

 the middle of the cutting edge, as in 

 Sargus wimaciilalus. Sometimes there is 

 a double notch, rendering the margin of 

 the tooth trilobate, as in Aplodactylus ; or it 

 may be divided into five lobes by a double 

 notch on each side of the central and largest 

 lobe, as in Boops. 



In the great Barracuda pike (Spln/reeita) the 

 crown of both the large and small lamellifonn 

 teeth is prolonged into a sharp point, closely 

 resembling a lancet. A similarly shaped pier- 

 cing and cutting tooth is in many of the Sharks 

 furnished with one or more accessory cusps at 

 its base, and the cutting margins of the tooth 

 are frequently notched, serrated, or crenated. 

 Prismatic teeth with three sides are fixed to the 

 jaws of Myletes ; and in some instances, as in 

 Scarus, they assume the shape of four-sided 

 prisms. 



The teeth of Fishesf present greater diversity 

 in their mode as well as in their place of attach- 

 ment than is observable in any other class of 

 animals. In a few instances they are im- 

 planted in sockets, to which they are attached 

 only by the surrounding soft parts, as, e. g. 

 the rostral teeth of the Saw-fish (Pristis). 

 Some have their hollow base supported, like 

 the claws of the feline tribes, upon bony pro- 

 minences which rise from the base of the 

 socket; the incisors of the File-fish (Batistes) 

 afford this curious example of a double gom- 

 phosis, the jaw and the tootli reciprocally 

 receiving and being received by each other. 



The teeth of Sphyrcena, Acanthums, Dic- 

 ti/odits, &c. are examples of the ordinary im- 

 plantation in sockets with the addition of a 

 slight anchylosis between the base of the fully 

 formed tooth and the parietes of the alveolar 

 cavity. But by far the most common mode of 

 attachment of fully formed teeth is by a con- 

 tinuous ossification between the dental substance 

 and the jaw, the transition being gradual from 

 the dental to the osseous tissue. The tooth 

 prior to its anchylosis is connected by ligamen- 

 tous substance, either to a plain surface, an 

 eminence, or a shallow depression in the bone. 

 Sometimes not the end, but one side of the 

 base of the tooth is attached by anchylosis to 

 the alveolar border of the jaw; it might be 

 supposed that in this case the crowns of the 



* Owen, Odontography, p. 2. 

 t Owen, loc. cit. 



3 R 



