SALMO LACUSTRIS. 



305 



and is truncated behind. The pectoral and ventral fins are pointed, and the 

 adipose fin, which does not reach farther back than the anal, is rather high, 

 and narrower at its base than in the upper part. 



The scales are very firm, and are distinguished by a strong silver lustre, 

 which varies in different parts of the body. The colour of the upper part of 

 the head is dark-green, becoming bluish-green on the sides, and bright silver 

 on the belly. Above the lateral line are small black flecks, which may be 

 round, but are usually angular or X-shaped. There are a few round black 

 spots on the operculum and on the dorsal fin. Below the lateral line the spots 

 are few. The pectoral, ventral, and anal fius are bluish-grey. The iris is 

 silvery. 



This fish is very voracious. According to Rapp, it enters the rivers Rhine 

 and 111 to spawn. Like other Trout, it is frequently sterile. The British 

 Museum contains sterile specimens, twenty-three inches long. In the back- 

 bone there are sixty to sixty-one vertebrae. It attains a weight of twenty-five 

 to thirty pounds. 



A variety of this species, known in Austria as the Maiforelle, Mailacks, or 

 Maiferche (Fig. 158), is limited to the larger mountain lakes, such as the Atter 



Fig. 158. SALMO LACVSTRIS VAR. SCHIFFERMULLERI (vALENCIENXES). 



See, Traun See, and Fuschler See, and may be conveniently distinguished as 

 Sal mo scJiiffermullerr (Valenciennes). 



In many respects it is similar to the Salmo lacustris, the height of the 

 body and length of the head being the same, and both about one-fifth of the 

 length of the fish. Von Siebold, however, regarded the 

 Sc/iwebforelle as simply the sterile form of the Maiforelle, 

 and while he united both in the Salmo lacnstris, included 

 other forms under the same name. 



In the May Trout the diameter of the eye does not exceed 

 one-fifth of the length of the head ; it is one and a half times its diameter from 

 the end of the snout. The nares are nearer to the snout than to the eye. The 

 20 



Fig. 159. FRONT 



VIEW OF VOMER 

 OF SALMO SCHIF- 

 FERMULLERI. 



