THYMALLUS VULGARIS. 357 



with small delicate scales. Naked patches occur on the throat on both 

 sides of the densely-scaled median line. These patches are larger in the young- 

 than in the old fish^ and probably have no importance in classification, though 

 Valenciennes founded a species, Thymallm gymnotliorax, on fishes which had 

 the belly naked and a hundred scales in the lateral line. 



The colour varies considerably with the condition of the fish, season of the 

 year, and age. The back is generally greenish-brown, becoming grey on 

 the sides, while the belly is silvery. The head is brown above, yellow at the 

 sides, with spots of black, which also occur in the fore part of the body, 

 especially over the lateral line, and brownish-grey longitudinal stripes run in 

 the direction of the rows of scales. The ventral and anal fins are violet, 

 often with brown transverse bands. The pectoral is yellow, becoming red at 

 spawning-time. The dorsal and caudal fins are bordered with black ; they are 

 generally red, and sometimes blue, and the dorsal commonly shows dai'k-brown 

 spots or bands extending horizontally. The caudal may also be decorated. In 

 the young fish the fins are transparent, and even the dorsal may be free from 

 spots. Some Swedish writers state that during the sj)awning season the usual 

 white colour of the belly becomes red. 



The number of pyloric appendages is small, varying from nineteen to 

 twenty-four. The last is conspicuously thicker than the others. The walls of 

 the stomach are very thick. The liver is not lobed. The air-bladder is very 

 long, and united to the abdominal walls ; it extends back behind the vent, 

 terminates in a point in fi-ont, and opens by a pneumatic duct into the ali- 

 mentary canal. Two kidneys extend along the length of the abdomen. There 

 are thirty-nine vertebraj in the thoracic region, and twenty-two in the tail, of 

 which eight extend into the fan of the caudal fin. There are thirty-six pairs 

 of ribs, and the accessory ribs are well-developed. Giinther mentions that in 

 the Neckar the stomach is infested with a parasite, Aacaru capsularia, and 

 with Citcullaniis salaris. 



The Grayling is eminently a lover of clear, rapid streams, and, like the 

 Trout, is more commonly met with in mountain brooks and small rivers than 

 where they empty themselves into lakes, a point of natural history which 

 Tennyson has recorded in his '' Brook " : — 



'• With here and there a lusty Trout, 

 Aud here and there a Gi'ayling." 



In the Lago Maggiore a Tlnjniallua occurs, which was named by Cuvier 

 and Valenciennes T. alianl, but its chief difference from T. viUgaria is in 

 having only seventeen rays in the dorsal tin, which is three fewer than in 

 T. r alga fix. It may be regarded as a local lake variety. 



