CAHP-iaSHES. 



r59 



Genls LEUCISCUS. 



Scales (ix (( I'll!'' nihldle-sized", mtmherinci in all the Scandinavian species about 40 — (!0 in the lateral line, vliirli 



is complete, ./airs projecting equally far, or nearlij so. Lobes of the caudal fin pointed. Base of the anal fn 



less than 1!> "> of the distance betn-een this fin and the tip of the snout. Distance between the dorsal fin and 



the tip of the snout less than SG % of that betKeen the anal fin and the same point. 



This genus was already known by its modern 

 name'', which means Whitefish, in tlie time of (talen 

 (the second centurA- A. D.). At many places, l)otli in 

 Sweden and elsewhere, Wiiitefish is a trivial name 

 common to the Cyprinoids (especiallj' Leuciscus and 

 Alburnus) and Coregonoids. Belon referred the name 

 of Leuciscus to the Dace, Rondelet both to the Roach 

 and the Dace. Klein, as we have mentioned above, 

 gave tiie genus a definition whicii corresponded in es- 

 sential respects to that of tiic modern subfamily Leu- 

 ciscince. Linnaeus did not recognise this genus — he 

 employed Ljeuciscus as one of his specific names for 

 the Dace — but Cdviek' adopted it as a subgenus; and 

 it was subsequently- raised by Fleming' to the rank of 

 an independent genus. The number of the species is 

 so gi'eat, about a hundred being known, that attempts 

 have witli reason been made to subdivide the genus. 

 But the ground on wliich most autliors, following Hec- 

 kel's example, have proposed to base this subdivision 

 — the immber and arrangement of the pharyngeal teeth, 

 their similarity or dissimilarity on the two pharyngeals 



and their distribution in one or two rows — has proved 

 untenable, as we ha,v(; already been enabled to conclude; 

 from the Minnow, whei'e the smaller row may some- 

 times disappear witliout leaving a trace of its presence. 

 The Scandinavian fauna contains only four recognised 

 species, which may lie distinguished as follows: 



.1 ; Aual iin concave. 



a: Least depth of the tail less than 

 43 'i of the length of the peduncle 

 of the tail between the perpendi- 

 culai- from the end of the base of 

 the anal fin and the middle point 

 in the line of demarcation between 



the scales and the caudal fin Leuciscus ffiislaciine. 



b: Least depth of the tail more than 

 43 % of the length of the peduncle 

 of the tail measured as above. 

 aa: Base of the dorsal fin less than 

 ' , of the distance between this 

 fin and the tip of the snout... Leuciscus iJus. 

 hi): Base of the dorsal fin more than 

 '/^ of the distance between this 

 fin and the tip of the snout... Leuciscus rutilus. 

 B: Anal fin cnnve.x Leuciscus ceplialus. 



" As for the exceptions, see tlje dbservations on the precciling genus. 



'■ From the Greek Aei'xog, wliitc-. 



' R'egne Animal, ed. I, torn. II, p. 194. 



'' Brit. Anim.. p. 187. 



