372 



ANATOMY OF VERTEBRATES. 



ii]iC'rior lii]£ir.\ 

 t(.'Otli i.-v 



Botcli on each side of tlie large middle lobe (Boops). In the 

 li)i'niidable Sca-jiikc (S])/i>/ra'ria Barracuda) the crown of each 

 tooth, large and small, is produced into a compressed and sharp 

 2.5,3 point, and resembles a lancet. Sometimes 



the edges of such lancet-shaped teeth are 

 finely serrated, as in Priodon, and the great 

 Sharks of the genus Curcharias, the fossil 

 teeth of which indicate a species ( Carch. 

 3[i'r/alodon) sixty or seventy feet in length. 

 The lancetted form is exchanged for the 

 stronger spear-shaped tooth in the Sharks 

 of the eenus Lamna, fi<x. 260 ; and in the 

 allied great extinct Otodus, as in the small 

 Porbeagle, similarly shaped, but stronger, 

 piercing and cutting teeth were complicated 

 by one or more accessory compressed cusps on 

 each side of their base, like the jMalay crease. 

 With respect to situation, the teeth, in 

 Sharks and Hays, are limited to the bones 

 (maxillary and mandibular), which form the 

 anterior ajicrture of the mouth : in the 

 Carp and cnlicr Cyprinoids the teeth are confined to the bones 

 (pharyngeal and Ijasioccijiital) which circumscribe the posterior 

 aperture of the mouth. The \yrasses {Lahruf:) and 

 the Parrot-fishes (^S'cflrM*) have teeth on the pre-max- 

 illary and pre-maudibular, as well as on the upper 

 and lower pharyngeals ; both the anterior and 

 piMtcrior apertures of the mouth being thus pro- 

 vided with instruments for seizing, dividing, or com- 

 minuting the food, the grinders being situated at 

 the pharynx. In most fishes teeth are developed 

 also in the intermediate parts of the oral ca^itv, 

 as on the palatines, the vomer, the hyoid bones, 

 the Ijrancliial arches ; and, though less commonly, on the pte- 

 rygoids, the entojitcrygoids and 

 the sphenoids. It is very rare to 

 find teeth developed on the true 

 superior maxillary bones ; but the 

 Herring and Salmon tribes, some 

 of the Ganoid Fishes, and the 

 great Sudis, fig. 86, i>i, arc ex- 

 ani]ilcs of this ajiproaeh to the 

 higher Vertebrates. Among the 

 anomalous positions of teeth may 



2J6 



Frmil (I'cMi of -\ 

 tlnrtylus. v. 



