TEETH OF FISHES. 647 



and arrangement of the teeth, adapting them to the diverse habits and 

 necessities of individual species ; and a few of these we must not omit 

 to notice in this place. 



(1766.) The My vine, or Hag-fish, one of the lowest of the entire class, 

 possesses no osseous framework to which teeth could be attached ; and 

 yet, from the parasitical life which this creature leads, it has need of 

 dental organs of considerable efficiency. The Myxine, feeble and help- 

 less as the casual observer might suppose it, is in reality one of the most 

 formidable assailants with which the larger fishes have to contend, since 

 neither strength nor activity avail aught in defending them against a 

 foe apparently so despicable. Fixing its mouth firmly to the skin of its 

 comparatively gigantic victim, the Myxine bores its way into its flesh 

 by means of a dental apparatus of a very extraordinary description. A 

 single fang-like tooth is fixed to the median line of the palate, and the 

 tongue is armed on each side with two horny plates deeply serrated : 

 thus provided, the Myxine, when it attacks its prey, plunges its palatine 

 hook into its flesh; and thus securing a firm hold, the lingual saws, 

 aided by the suctorial action of the mouth, tear their way to its very- 

 vitals*. 



(1767.) In the Lamprey the whole interior of the mouth is studded 

 with horny teeth, not merely fixed to the palate and tongue, but to the 

 cartilaginous representative of the inferior maxilla and to the inner 

 surface of the lips. 



(1768.) In the Carp tribe (Cyprinidce) the jaws are destitute of teeth ; 

 but in the throat there is a singular apparatus serving for the mastica- 

 tion of their food. The basilar bone at the base of the skull supports 

 a broad three-sided dental plate, which might be compared to an anvil ; 

 while the two inferior pharyngeal bones are each armed with four or 

 five large teeth, so disposed that, by working upon the piece first men- 

 tioned, they bruise and triturate the aliment before it is permitted to 

 pass into the digestive cavity. 



(1769.) In Skates (Baidce) the internal surface both of the upper 

 and lower jaws is so covered with teeth, that they have the appearance 

 of a tessellated pavement : these teeth are sometimes flat and smooth, so 

 as to be merely useful in crushing prey ; but in many species they are 

 prolonged into sharp hooks adapted to prehension. 



(1770.) In Sharks a beautiful provision is met with. Several rows 

 of teeth placed one behind the other are found laid flat, and concealed 

 behind the jaw. One row only, composed of triangular cutting teeth, 

 stands erect and ready for use ; but when these fall off, blunted and un- 

 fit for service, the next row rises to take their place ; and thus a succession 

 of efficient weapons are given to these terrific monsters of the ocean. 



* Professor Owen, Odontography ; or a Treatise on the Comparative Anatomy of 

 the Teeth, their Physiological Eelations, Mode of Development, and Microscopic 

 Structure,' &c. 4to. Bailliere, 1840. 



