77 



at the base, which ii obliquely truncated, and rounded and obtute at the apex. The mrwal 

 pair is alight ly curved, and is the largest ; the re*t derreaiie in siie to the outermost. T In- 

 external facet of each tooth is covered with a mooth, deiue, enamel-like substance, which, 

 towards the apicv* of the teeth, presents a yellow colour, and rails to mind the peculiar colour 

 of the enamel in some of the Rodentia. These outer maxillary teeth are arranged in close 

 contact with one another. The form of the alveolus in which the base of each tooth is fixed, 

 is peculiar in the dental system, resembling rather the surface of attachment for the cUw in 

 the lingual phalanges of the feline quadruped*. A conical process of the bone rises from thr 

 middle of the alveolar depression, and is adapted to the cavity in the base of the tooth. The 

 circumference of the base of the fully-formed tooth is attached by a slight anchylosis to thr 

 margin of the alveolus, but the confluence of the tooth with the bone is much leas complete 

 than in many other fishes. In the left prcmaxillary the successors of the external teeth have 

 been exposed by removing thr outer wall of their alveoli. These cavities communicate with 

 the outer side of the jaw by foramina situated on the outer side of the base of the teeth in 

 place. The teeth of the posterior row, which are peculiar to the upper jaw, are six in num- 

 ber, three in each intermaxillary bone ; they present the form of elliptical plates, compressed 

 laterally, rounded at the base and slightly pointed at the apex. Thr anterior tooth is the 

 largest, measuring six lines in length and three in breadth, but scarcely half a line in thick- 

 ness ; the two other teeth progressively diminish in size. These posterior teeth lie in clow 

 juxtaposition with the outer row, and like the posterior small upper incisors of the hare and 

 rabbit, receive part of the appulse of the inferior teeth. They are affixed by a very obliqnr 

 and slightly excavated base to a shallow alveolus, having a convex rising of bone in its middle. 

 They are also deciduous, and the presence of well-developed reserve teeth in cavities of the 

 jaw, immediately internal to those of the exterior row, would indicate that the succession of 

 teeth of the inner row is likewise unlimited. The foramina leading to the cavities of thr 

 succe&sional teeth are seen immediately above the bases of the teeth in place ; the grrms of 

 the successors of the inner row of teeth are exposed in their alveoli in the left intermaxillary 



bone. 



llmttfria*. 



329. The branchial and phanngcal arches of the Balitles forcipatiu, with the dried 

 gills. 



The pharyngeal teeth are small, conical, compressed, curved and sharp-pointed : there are 

 two regular and equal rows above, one on each of the posterior pharyngobranchial bones. 

 The inferior pharyngeal bone supports two unequal rows of teeth, the anterior the smallest . 

 The curvature of the upper and that of the lower pharyngeal teeth are reversed, and they 

 thus form a kind of carding- machine, well-adapted for ' teasing ' the bruised and coarsely 

 divided seal-weeds and other marine nutrient substances. The orifices of the alveoli of thr 

 concealed germs of the succeninnal teeth may be seen behind the bases of the posterior row. 

 and in front of those of the anterior row of the lower pharyngeal teeth. 



Htmteria*. 



