SALMON. 



the situation of the row of teeth that are fixed on the cen- 

 tral bone of the roof of the mouth, called the vomer : 

 Nos. 2, 2, refer to the teeth on the right and left palatine 

 bones ; and the row of teeth outside each palatine bone 

 on the upper jaw are those of the superior maxillary bones : 

 No. 3, refers to the row of hooked teeth on each side 

 of the tongue, outside of which are those of the lower 

 jaw-bones. The Trout is chosen as showing the most 

 complete series of teeth among the Salmonida; and the 

 value of the arrangement, as instruments for seizure and 

 prehension, arises from the interposition of the different 

 rows, the four lines of teeth on the lower surface alternating 

 when the mouth is closed with the five rows on the upper 

 surface, those on the vomer shutting in between the two 

 rows on the tongue, &c. 



The second figure represents, in outline, a side view of 

 the head, of which No. 1 is the preoperculum ; No. 2, 

 the operculum ; No. 3, the suboperculum ; No. 4, the 

 interoperculuni ; No. 5, the branchiostegous rays : the four 



