SALMO FARIO, VAR. AUSOXII. 



291 



their diameter, so that the frontal space is rather large. The fold at the 

 outer margin of the eye, or rudimentary eyelid, is broad and thick. The small 

 round nares are nearer to the eye than to the snout. There is an indistinct, 

 very oblique lower limb to the pre-operculum. The maxillary bone is strong 

 and expanded, longer than the snout, and extends below the posterior margin of 

 the orbit. When the mouth is closed the mandible is shorter than the upper 

 jaw, though it is broad and powerful. The snout is produced in the male, 

 and the lower jaw in old males has a terminal hook, which is received into 

 a deep depression of the extremity of the upper jaw, so as to keep the jaws 

 apart. 



The teeth are strong and well -developed. They are larger in the man- 

 dible and pre-maxillary than in the maxillary and palatine bones. The head 



Fig. 150. SALMO FARIO, YAK. AVSONII 



of the vomer is triangular, broader than long, carrying a transverse series of 

 teeth, while on the body of the bone there is a double series of strong teeth, 

 which may be parallel or alternate. All the teeth of the mouth have their 

 points curved inward. There are four or five teeth in a row on each side 

 of the tongue. There is some variation in the dentition with sex. 



As in all members of the group, the gill-opening is wide. The number of 

 branchiostegal rays is nine on the right side, and ten on the left. The gill- 

 arches are of moderate length, and their pointed rake-teeth are not 

 numerous. The last arch has usually only seven to eight short, blunt, finely 

 curved teeth. 



The ventral and dorsal contours of the fish are similar. The dorsal fin 

 commences a little in front of the middle of the body. It is rather sharply 

 truncate, and nearly as long as high. The four anterior rays of this fin are 

 rudimentary, and covered by the skin. The adipose fin is opposite the 



