DACE. 
761 
Leuciscus vulgaris , Flmng, Brit. Anim ., p. 187; Cuv., Val., 
Hist. Nat. Poiss., vol. XVII, p. 202 (+ Leuc. rostratus 
(ex. Agass.) + L. rodens (ex. Agass.) + L. lancastriensis, 
(ex. Sijaw), p. 216 + ]j. burdigalensis , p. 218, nec L. gris- 
lagine, p. 220); Gthr, Cat. Brit. Mus., Fish., vol. VII, p. 
226; Day, Fish. Gt. Brit.. Irel., vol. II, p. 180, tab. 
CXXXIII, tig. 1; Mob., IIcke, Fiscli. Osts., p. 109. 
The Dace is one of the smaller species of the ge- 
nus. Its ordinary length is between 15 and 20 cm., 
and in Sweden probably does not exceed 25 cm. 
Further south it seems to attain a somewhat greater 
size; Fatio found in the Rhine a gravid female of this 
species, 275 mm. long and 300 grammes in weight. 
Day states that in the Thames the Dace attains a length 
of about 3 dm. 
Of all the Scandinavian species within the Leucis- 
cine subfamily the Dace is the most elongated in pro- 
portion to the depth of the body, and is easily recog- 
nised by this character. The body is deepest a little 
in front of the dorsal fin, and the greatest depth mea- 
sures in adult specimens, 18 — 21 cm. long, about 21 
— 24 % of the length of the body. In younger speci- 
mens the greatest depth is even relatively less, as else- 
where in the family. The least depth of the body (of 
the peduncle of the tail) measures in adult specimens 
about 8 V 2 — 7 Vs % of its length. The back is terete, 
though less so just in front of the dorsal tin, and the 
sides are moderately compressed. The back rises in a 
gradual curve from the head to a. point a little in front 
of the dorsal tin, though it is straighter than in the 
Scandinavian congeners of the Dace, and the curve does 
not increase in sharpness at the occiput. From this 
point the dorsal profile slopes gently, almost in a straight 
line, to the base of the caudal fin. The ventral profile 
forms a similar or even more gradual curve from the 
chin to the vent, which protrudes slightly, and then 
runs straight to the caudal fin. 
The head is of moderate size (in adult specimens 
about 21 — 19 % of the length of the body), with broad 
and rather flat forehead, sloping 'with a slight convexity 
towards the broad and very obtuse snout, which pro- 
jects a little in front of the jaws. The mouth is small 
and turns slightly upwards, as in the rest of th e -Leu- 
ciscince , the upper jaw is slightly more prominent than 
the lower, and the corners of the mouth extend a little 
behind the perpendicular from the posterior nostril. 
The length of the upper jaw from the middle of the 
tip of the snout measures in adult specimens rather 
more than 1 / i (about 25 V 2 — 28 %) of that of the head. 
The length of the lower jaw is equal to or somewhat 
greater than that of the snout, or about V 3 (32 — 35 %) 
of that of the head. The eyes are fairly large, their 
longitudinal diameter being only slightly less than 1 4 
(about 23 — 24 V 2 %) of the length of the head. They 
are generally set just in front of the middle of the 
head" and so high that the line drawn from the middle 
of the caudal fin to the margin of the upper jaw 
touches the inferior margin of the eye. The least 
breadth of the interorbital space is about 1 / 3 (32 x / 2 — ^ 
34 %, exceptionally 37 %) of the length of the head, or 
1V 2 — lVs times the longitudinal diameter of the eyes. 
The nostrils are rather large, and lie in a deep cavity, 
nearer to the eye than to the tip of the snout. The 
gill-rakers are small and scattered, but pointed, num- 
bering 8 in the outer row on the first branchial arch 
and 7 on the pharyngeal bones. Each pharyngeal is 
armed as a rule with 7 teeth (fig. 189), set in two 
rows. The inner roAv contains 5 long and fairly straight 
teeth, curved up Avar ds at the tip, but usually not much 
hooked 6 , and Avithout incisions or spines on the indi- 
stinct masticatory surface. The teeth in the outer roAv 
are generally 2, sometimes 3, in number, short, straight, 
and conical. The pharyngeal cartilage is soft, thin at 
the edges, heart-shaped, and deciduous. The gill- 
openings do not extend at all above the upper margin 
of the gill-cover, and beloAv they coalesce Avith the 
isthmus at a distance from each other of about half 
the diameter of the eyes. 
The dorsal fin, the height of Avhich is greater than 
its length at the base, lias an obliquely truncate mar- 
gin Avith somewhat rounded corners. Behind it is half 
as high as in front, a rule Avhich applies to most of the 
Leucisenue. It begins at a distance from the tip of the 
snout Avhich in adult specimens measures on an average 
half the length of the body, varying, hoAvever, between 
46 V 2 and 54 % thereof. Its base occupies 7 10 (varying 
in our specimens between 9 1 / 2 and 10V 2 %) of the length 
of the body; and its height (the length of the longest 
ray), Avhich is as a rule equal to the length of the 
pectoral fins, varies in our specimens between 15 and 
1 6 1 / 3 % of the length of the body. The first three rays 
a 
depending 
b 
The postorbital length of the head varies in onr specimens between 4 8 1 / 2 and 54 % of its entire length, the 
on the breadth of the opercular rim. 
In specimens from Lake VVener, however, we find the hooked tips well developed in the two hindmost teeth 
variations essentially 
of this row. 
