CARP-FISHES. 
759 
Genus LEUCISCUS. 
Scales as a rale middle-sized", numbering in all the Scandinavian species about 40 — 60 in the lateral line, which 
is complete. Jaws projecting equally far, or nearly so. Lobes of the caudal fin pointed. Base of the anal fin 
less than 19 % of the distance between this fin and the tip of the snout. Distance between the dorsal fin and 
the tip of the snout less than 86 % of that between the anal fin and the same point. 
This genus was already known by its modern 
name * 6 , which means Wliitefish, in the time of Galen 
(the second century A. D.). At many places, both in 
Sweden and elsewhere, Whitefish is a trivial name 
common to the Cyprinoids (especially 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 the genus a definition which corresponded in es- 
sential respects to that of the modern subfamily Leu- 
ciscince. Linnaeus did not recognise this genus — he 
employed Leuciscus as one of his specific names for 
the Dace — but CuvieiT adopted it as a subgenus; and 
it was subsequently raised by Fleming' 7 to the rank of 
an independent genus. The number of the species is 
so great, about a hundred being known, that attempts 
have with reason been made to subdivide the genus. 
But the ground on which most authors, following Hec- 
kel’s example, have proposed to base this subdivision 
— the number 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 have already been enabled to conclude 
from the Minnow, where the smaller row may some- 
times disappear without leaving a trace of its presence. 
The Scandinavian fauna contains only four recognised 
species, which may be distinguished as follows: 
A: Anal fin concave. 
a: Least depth of the tail less than 
43 % of the length of the peduncle 
of the tail between the perpendi- 
cular 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 grislagine. 
b: Least depth of the tail more than 
43 % of the length of the peduncle 
of the tail measured as above. 
a a : Base of the dorsal tin less than 
\ 4 of the distance between this 
fin and the tip of the snout... Leuciscus idus. 
bb: Base of the dorsal fin more than 
l / 4 of the distance between this 
fin and the tip of the snout... Leuciscus rutilus. 
B: Anal fin convex... Leuciscus cephalus. 
a As for the exceptions, see the observations on the preceding genus. 
6 From the Greek hevx.6g, white. 
c Regne Animal , ed. I, tom. II, p. 194. 
d Brit. Anim., p. 187. 
Scandinavian Fishes. 
96 
