TEETH. 



877 



chiefly on animal matter must vary according 

 as th fir food may be common salt fish, or 

 shell-fish." " Such fish as live on the first kind 

 have, like the carnivorous quadrupeds and 

 birds, no apparatus I'or mastication, their teeth 

 being intended merely for catching the food 

 and fitting it to be swallowed. But the shells 

 of the second kind of food render some de- 

 gree of masticatory power necessary to fit it 

 for its passage either into the stomach or 

 through the intestines : and accordingly we 

 find in certain fish a structure suited to the 

 purpose. Thus the mouth of the Wolf-fish is 

 almost paved with teeth, by means of which 

 it can break shells to pieces, and fit them for 

 the oesophagus of the fish, and so effectually 

 disengage the food from them, that though it 

 lives upon such hard food, the stomach does 

 not differ from that of other fish." 



But in order to secure the capture of the 

 shell-fish, the teeth of the Wolf-fish are not all 

 crushers ; some present the laniary type, with 

 the apices more or less recurved and blunted 

 by use, and consist of strong cones spread 

 abroad, like grappling hooks, at the anterior 

 part of the mouth.* 



The premaxillary teeth are all conical, and 

 arranged in two rows ; there are two, three, 

 or four in the exterior row, at the mesial half 

 of the bone, which are the largest ; and from 

 six to eight smaller teeth are irregularly 

 arranged behind. There are three large, 

 strong, diverging laniaries at the anterior end 

 of each premandibular bone, and immediately 

 behind these an irregular number of shorter 

 and smaller conical teeth, which gradually 

 exchange this form for that of large obtuse 

 tubercles ; these extend backwards, in a double 

 alternate series, along a great part of the 

 alveolar border of the bone, and are termi- 

 nated by two or three smaller teeth in a single 

 row, the last of which again presents the 

 conical form. Each palatine bone supports 

 a double row of teeth, the outer ones being 

 conical and straight, and from four to six in 

 number ; the inner ones two, three, or four in 

 number, and tuberculate. I have seen a spe- 

 cimen where the inner row was wanting on 

 one side. The lower surface of the vomer is 

 covered by a double irregularly alternate 

 series of the same kind of large tuberculate 

 crushing teeth as those at the middle of the 

 premandibular. All the teeth are anchylosed 

 to more or less developed alveolar eminences, 

 like the anterior teeth of the Lophius. The 

 periphery oftthe expanded circular base of the 

 large anterior grappling teeth is divided into 

 processes indicative of the original ligamen- 

 tous fasciculi at the base of the pulp by the 

 ossification of which their anchylosis is ef- 

 fected. 



When such anchylosed teeth and the sup- 

 porting bone are divided by a vertical sec- 

 tion, as in fig. 2, pi. 66, of my " Odonto- 

 graphy," there may be generally discerned a 

 faint transverse line indicating the original 

 separation between the tooth and the bone, 



and more clearly defining the dental from the 

 osseous structure, than in the anchylosed teeth 

 of other fishes. From the enormous develop- 

 ment of the muscles of the jaws, and the strength 

 of the shells of the whelks and other testacea 

 which are cracked and crushed by the teeth, 

 their fracture and displacement must obviously 

 be no unfrequent occurrence ; and most speci- 

 mens of the jaws of the Wolf-fish exhibit some 

 of the teeth either separated at this line of 

 imperfect anchylosis, or, more rarely, broken 

 off above the base, or, still more rarely, de- 

 tached by fracture of the supporting osseous 

 alveolar process. 



With regard to the substance of the teeth 

 of fishes, the modifications of dentine, called 

 vaso-dentine and osteo-dentine *, predomi- 

 nate much more than in the higher Verte- 

 brata ; and they thus more closely resemble 

 the bones which support them. There is, 

 however, great diversity in respect of sub- 

 stance. The teeth of most of the Chaeto- 

 donts are flexible, elastic, and composed of a 

 yellowish subtransparent albuminous tissue ; 

 such, likewise, are the labial teeth of the He- 

 lostome, the premaxillary and mandibular 

 teeth of the Goniodonts, and of that percoid 

 genus thence called Tric/iodon. In the Cy- 

 clostomes the teeth consist of a denser albu- 

 minous substance. The upper pharyngeal 

 molar of the Carp consists of a peculiar brown 

 and semitransparent tissue, hardened by salts 

 of lime and magnesia. The teeth of the Fly- 

 ing-fish (ExoccEtus), and Sucking-fish (Re- 

 morci), consist of osteo-dentine. In many 

 fishes, e.g. the Acanthurus, Sphyrcejm, and 

 certain Sharks (Lamna, Jig. 545.), a base, or 

 body of osteo-dentine is coated by a layer of 

 true dentine, but of unusual hardness, like 

 enamel : in Prionodon this hard tissue predo- 

 minates. In the Labrus the pharyngeal crush- 

 ing teeth consist w holly of hard or unvascular 

 dentine (Jig. 54-4.). In most Pycnodonts and 

 Cestracionts, and many other fishes, the body 

 of the tooth consists of ordinary unvascular 

 dentine, covered by a modification of that 

 tissue which I have called " vitro-dentine " from 

 its clear, polished, enamel-like character : but 

 this is not enamel, nor the product of a dis- 

 tinct organ from the dentinal pulp : it differs 

 from ordinary dentine in the greater propor- 

 tion of the mineral particles, their more mi- 

 nute diffusion through the gelatinous basis, in 

 the straighter course and more minute size 

 of the calcigerous tribes ; it results from the 

 calcification of the external layer of the den- 

 tinal pulp, and is the first part of the tooth 

 which is formed. In Sargus and Batistes 

 the body of the tooth consists of true dentine, 

 and the crown is covered by a thick layer of 

 a denser tissue, developed by a distinct organ, 

 and differing from the " enamel " of higher 

 animals only in the more complicated and or- 

 ganised mode of deposition of the earthy salts. 

 The ossification of the capsule of the complex 

 matrix of these teeth covers the enamel with 

 a thin coating of " cement." In the pharyngeal 



* Odontography, pi. GO, Gl. 



Odontography, Introduction, p. Ixxii. 



