LEUCISCUS RUBELLA. 143 



and become relatively small in old age. They are too short to reach to the 

 venti-als. The ventral fins extend to the vent. The terminal rays of the 

 caudal fin are longer than the head. The lateral line descends from the upper 

 angle of the operculum towards the ventral fin in a concave curve, rising again 

 to the middle of the tail. Under the dorsal fin the lateral line is in the lower 

 third of the body. 



The largest scales on the lateral line are longer than the diameter of the 

 eye; they are similar to those of the Roach, and are strong. Consecutive strife 

 surround a central thickening, and there is 

 a variable number of radiating rays, usually 

 five to six, but sometimes as many as eleven, 

 between which the rounded border of the 

 scale is festooned. The smallest scales are 

 towards the two extremities of the body, and 

 along the middle of the back. 



The colour of the back is a pale olive- ^'S- 7L-pharvngeal teeth of leu- 



■*- CISCUS AULA, 



green, but the sides ai*e sometimes golden- 

 green and sometimes yellow. A broad black band extends about the lateral 

 line from the caudal fin to the operculum. A golden band often exists above 

 it. The abdomen is silvery-white, with more or less of a golden tinge. The 

 fins are colourless, but exhibit some amount of variation with age, season, 

 and locality. They are sometimes grey, and the pectoral, ventral, and anal may 

 have a yellowish or reddish tinge. The colours become a little dim with age. 



This fish does not often exceed six inches in length. 



According to Fatio, the males are relatively few. At the breeding season 

 they have the first ray of the pectoral fin thickened. 



The air-bladder is large and constricted in the middle. There are thirty-six 

 vertebrae. The pharyngeal teeth are in a single row of five on each side, and 

 resemble those of the Roach (Fig 71). 



The species is common in the north of Italy in both lakes and streams, 

 and is provincially known as Tr/otfo. It is found in Dalmatia, and in 

 Spain and Portugal. It is nowhere valued as food. 



There are two varieties of this species recognised by Heckel. The variety 

 which, following Bonaparte, he names L. rubella (See Frontispiece) has the 

 form more elongated, and the head higher than in L. aula, with the dorsal and 

 anal fins higher than long. The body is said to be always four times as long as 

 high, and five times as long as the head. The dorsal profile forms a flat arch, 

 in front of the dorsal fin; as compared with Leiiciscus aula, the dorsal fin is 

 relatively higher in this variety, and has the base shorter. The back has a 

 dark brownish-green colour ; the pectoral, anal, and ventral fins are reddish ; 



