352 THE FRESn-WATER FISHES OF EUROFE. 



The flavour is compared to that of the Smelt^ and the fish is res^arded as 

 a delicacy, probably, Jardine remarks, on account of the difficulty of always 

 obtaining" a supply ; thoug-h Yarrell, writing from practical experience, says he 

 considers the fish (piite entitled to its high character for excellence. 



Without the caudal fin the fish is four times as long- as high. The total 

 length is five and a quarter times that of the head, and the diameter of the 

 eye is about one-third of the length of the head, so that it is long-er than 

 the snout. The lower jaw is the longer. The small mouth contains a few 

 minute teeth on the tongue; the ventral and dorsal profiles are similar. The 

 lateral line is in the middle of the side ; the longest rays of the dorsal fin are 

 twice the length of its base. The adipose fin is near the caudal ; the ventral 

 fin begins under the front part of the dorsal. The fins are all conspicuously 

 long, though the pectoral is shorter than the head. 



The colour of the upper part of the body is a dull greenish or bluish tint, 

 while the sides and lower part of the body are silvery, though the colour varies 

 with the nature of the bottom. The dorsal fin takes the colour of the back, 

 and there is a paler colour of the same tint in the fins of the lower part 

 of the body. There are fifty-six vertebrae in this species, which is two fewer 

 than in the Powan. 



In Russia Dr. Grimm enimierates many other species of Coregonus, such as 

 C. vcliiin (Pallas) in Lake Koobin, in the Dwina and rivers of Siberia; C. 

 polkur (Pallas) and C. omul (Lepechin), both occur in the Mezen andPetchora; 

 C. p('J('(l in the Petchora only; C. fera (Jurine) ; C. Baeril (Kessler), in 

 Lakes Ladoga and Onega; C. maneita (Bloch) in Lake Peipus and the lakes 

 in Poland ; and C. I.scliolmur/ensis (Dauilewski) found only in Lake Onega. 



Genus : ThymalluS (Cuvier). 



The genus Thymallus is found in the temperate parts of the northern 

 hemisphere, occurring in North America, Northern Asia, and Europe. Its 

 most distinctive characters are the great length and size of the dorsal fin, 

 which includes from thirteen to twenty-three rays; and secondly, the mouth 

 and maxillary bones are small and furnished with teeth, which, though small, 

 are developed on the jawbones, the head of the vomer and palatine bones, and 

 are absent from the tongue. The ])yloric aj)pendages to the intestine are less 

 numerous than in Coregonus or Salmo. The stomach is horse-shoe-shaped ; 

 the air-bladder is very large. 



The only J^]uropean examples are the widely distributed Tl/j/iini/hts ru/;/(ir/x, 



