CHUB. 
771 
(72 — 89 %, according to our measurements) of the same. 
The gill-rakers are short and scattered, their number in 
the outer row on the first branchial arch being about 
the same as in the Ide (9 — 11), most of them simple, 
but at least the middle ones in old specimens branched 
at the tip, as in the Ide. The pharyngeal teeth (5 
large ones in the inner row, and 2, a little more than 
half as large, in the outer) are distinguished (fig. 191) 
for their strength, their sharp, hooked tip, and the 
tendency to pectination indicated by the small, terete 
protuberances on the masticatory surface. The pseudo- 
branchiae are well-developed. 
The dorsal fin, the position of which is such that the 
anterior margin lies in a line with the termination of the 
insertions of the ventral fins, is rather more than twice 
as high in front as behind, and its superior margin is 
truncate, slightly rounded. In old specimens its shape 
and backward direction are as represented in our figure; 
but in young Chub it is quite upright, with pointed 
front angle. It begins at a distance from the tip of 
the snout measuring about 48 — 50 % of the length of 
the body; its height is about 17 — 15 %, and the length 
of its base about 9 or 10 %, of the same. Thus its 
base is generally equal to or slightly less than the least 
depth of the body", a point which among our Cypri- 
nines is especially characteristic of the Chub, though 
subject to exceptions, just as in young Ide the least 
depth of the body may exceptionally be equal to the 
length of the base of the dorsal fin. The structure of 
the anal fin is unparalleled among our Cyprinines, and 
thus affords a character excluding all possibility of con- 
fusion between the Chub and other species. In all the 
others there is a considerable difference in the height 
of the fin behind and in front, the last ray being often 
not half as long as the fourth or the longest anterior 
ray. But in the Chub the difference is not so great, 
the length of the last ray being at least about 56 — 60 
% of that of the fourth. Nor is this all: the margin 
of this fin in the Chub is convex, when expanded, the 
middle rays too being comparatively longer than in the 
rest of our Cyprinines, sometimes, in old specimens, 
the longest in the whole fin. This is the case in our 
figure, and we will only add that the fin may be still 
more strongly expanded than it is there, and that the 
margin then forms a complete curve, the greater the 
older the fish. The anal fin begins at a distance from the 
tip of the snout measuring about 64 — 67 %, its length 
is about 8 — 11 %, and its height about 12 or 18 % (in 
exceptional cases 14 %), of the length of the body. The 
caudal fin resembles that of the Ide, but is generally 
not so deeply forked, its middle rays occupying between 
about 9 % and a little over 8 % of the length of the 
body, and measuring in young Chub about half or rather 
more than half, in old about 48 or 47 %, of the length 
of the longest caudal rays. 
The pectoral and ventral fins resemble those of the 
Ide. The length of the former is about 17- — 16 % of 
the length of the body, that of the latter about 15 — 14 
% (in the females exceptionally 13 %) of the same. The 
distance between the ventral fins and the tip of the 
snout is about 46 % (in exceptional cases 47 or 48 °/o) 
— 44 % 1 that between these fins and the pectorals (the 
preabdominal length) about 23 — 26 % (sometimes 27 %), 
and that between them and the beginning of the anal 
fin (the postabdominal length) about 19 — 22 %, of the 
length of the body. 
The scales are comparatively large and thick, but 
otherwise resemble in form and texture those of the 
Ide. The lateral line, which first descends in a curve 
and then runs nearer to the belly than to the back, is 
generally covered by 45 scales, a number which in the 
Scandinavian Chub examined by us varies only between 
44 and 46, in exceptional cases 47. According to other 
writers, however, the variation extends, as mentioned 
above, between 39 and 48. The lateral line is generally 
separated from the anterior part of the base of the 
dorsal fin by 7 rows of scales, and from the ventral 
fins by 4 rows. 
Full-grown Chub display a handsome and varied 
coloration on a silvery gray ground, most like the colours 
of the Roach. The back is dark olive green, the scales 
are tipped with a metallic lustre. On the sides above 
the lateral line the bases of the scales are dark olive 
green, thus forming as it were dark frames within which 
their lustrous tips are still more prominent. Below the 
lateral line this dark setting fades and gradually dis- 
appears, the scales acquiring a more yellowish tinge, 
which grows more distinct on the belly. Behind the 
a In 11 specimens 17 — 42 cm. long the average length of the base of the dorsal fin in % of the length of the body is 9‘3, and 
the average for the least depth of the tail 9'4. In 5 specimens 37 — 89 mm. long, on the other hand, the corresponding averages are re- 
spectively 9’9 and 91, so that the character is not distinct until the fish has attained a length of about 1 1 / 2 dm. 
