186 SALMONID^. 



bone, and forming one-fifth of tlie length, excluding the 

 caudal. 



The eyes are large, and situated a little more than a diameter 

 of the orbit from the tip of the snout, and nearly thrice as 

 far from the edge of the gill-plate. The nostrils are placed 

 mid-way between the orbit and the snout. The snout is 

 blunt when seen in front, but its profile is more acute. The 

 mouth has a small orifice, but, when shut, its angles are 

 depressed. 



The jaws and tongue are furnished with a few teeth, which 

 are too minute to be readily seen by the naked eye, and too 

 slender to be very perceptible to the finger. The vomer and 

 palate are quite smooth. 



Of the gill-covers, the pre-operculum is sharply curved, and 

 rather broad ; its width, in the middle, equalling the height of 

 the sub-operculum. The operculum measures one-third more 

 vertically than it does horizontally ; while, on the contrary, the 

 sub-operculum is twice as long as it is high. The inter -operculum, 

 is triangular. The branchial arches have each a single row of 

 erect subulate rakers, a quarter of an inch long, and rough on 

 their inner surfaces. The pharyngeal bones are inconspicuous 

 and toothless. 



The scales are large, irregularly orbicular, and about half an 

 inch in diameter, with a bright pearly lustre. 



Colour, in the shade, bluish grey on the back, lighter on the 

 sides, and white on the belly, giving place to a nacry and 

 iridescent pearly lustre in a full light. Cheeks, opercula, and 

 irides, thickly covered with nacre. 



Fins : branchiostegous rays, eight ; dorsal, fifteen ; pectoral. 



