(72 — 89 %, accordiiiij: to our ineasuiTiiicnts) of the same. 

 The gill-rakers are short and scattered, their number in 

 the outer row on tlie first branchial arcli being a])out 

 the same as in the ide (9 — 11), most of them simple, 

 hut at least the middle ones in old s])eeinu'ns branched 

 at the tip, as in the Ide. Tlie pharyngeal teeth (5 

 large ones in tlie inner row, and 2, a little more than 

 half as large, in tlie outer) are distinguished (fig. 191) 

 for their strength, tlieir sjiarp, hooked tip, and tlie 

 tendency to pectination indicated l)y the small, terete 

 protuberances on the masticatory surface. Tiie pseudo- 

 i)ranchiffi are well-developed. 



The dorsal fin, tiie [losition of wiiich 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, sligiitly i-ounded. In old specimens its shape 

 and backward direction are as represented in our figure; 

 but in young Chub it is quite upright, with pointed 

 fi'out 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 [loint which among our Cypri- 

 nines is especially characteristic of the Chub, thougji 

 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 tin. 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 tin 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 tlie whole fin. This is the case in our 

 figure, and we will only add that the tin mav be still 

 more strongly expanded than it is tliere, and that the 



IB. 771 



margin tlieii forms a com])lete curve, the greater the 

 old(>r the fisli. Tlie anal llii l)egiiis at a distance from the 

 tip of the snout measuring about 64 — 07 %, its length 

 is about 8 — 11 %, and its height about 12 or \?> % (in 

 exceiitional cases 14 %), of the lengtii of the body. The 

 caudal fin resembles that of the Ide, but is generally 

 not so deeply forked, its middle rays occupying between 

 aliout 9 ''„ and a little o\er 8 % of tiie lengtii of the 

 bod}', and measuring in young Cliub about half <jr rather 

 more tiian lialf, in old about 48 or 47 %, of the length 

 of the longest caudal rays. 



Tlu! [lectoral and ventral tins resemble those of tiie 

 Ide. Tiie length of the former is about 17 — K! % 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 %) 

 — 44 %, 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 

 tin (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 silveiy gray ground, most like the colours 

 of the Koach. 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. Relow the 

 lateral line this dark setting fades and gradually dis- 

 appears, the scales acquiring a more yellowish tinge, 

 which grows more distinct on the liellv. Behind the 



"In 11 specimens 17 — 42 cm. long the average lengtii of the base of the dorsal fin in % of tlie length of the body is 9'3, and 

 the average for the least depth of the tail 94. In 5 specimens 37 — 89 mm. long, on the other hand, the corresponding averages are re- 

 spectively 99 iind 91, so that the character is not distinct until the fish has attained a length of about 1 ' ^ dm. 



