37G ANATOMY OF VERTEBRATES. 



the walls dividing the vaulted cavities containing; the c^rms of the 



o o 



new teeth ; the roofs of these cavities yield to the absorbent 

 process consequent on the growth of the new teeth without 

 materially weakening the attachment of the old teeth, and without 

 the new teeth being subjected to any pressure until their growth 

 is sufficiently advanced to enable them to bear it with safety ; by 

 this time the sustaining borders of the old alveolus are under- 

 mined, and the old worn-down tooth is shed. 



The dental system of the Wolf-fish (Anarrliiclias Lupus), is 

 adapted for feeding on hard Crustacea and testacea. But, in 

 order to secure the capture of the shell-fish, the teeth of the 

 Wolf-fish are not all crushers ; some present the lam'ary 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. 1 



The premaxillary teeth are conical, and arranged in two rows. 



v O 



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 backward, in a double alternate series, along a great 

 part of the alveolar border of the bone. 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. The lower surface of 

 the vomer is covered by a double irregularly alternate series of 

 the same kind of large 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. 



From the enormous developement 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 specimens of the jaws of the Wolf-fish exhibit some of the 

 teeth separated at the line of anchylosis, or broken off above the 

 base. 



With regard to the substance of the teeth of Fishes, the 

 modifications of dentine, called vaso-dentine and osteo-dentine, 

 predominate much more than in the higher Vertebrates, and they 

 thus more closely resemble the bones which support them. The 



1 v. pi. GO, 61. 



