74r) 



tha 



If that of the 



IS arr similar io eacii (itlicr in general 

 form, \\licn tlic \entrals aw not fully expanded. Uotli 

 i)airs are of an ol)li(|ne o\al sliajK'; hnt the iieetiiral 

 fins are more pointed and lonuer. The len<i;'th of tiie 

 latter \aiMes l)etween ahont 'lU and 1.') "o. that of the 

 ventral tins lietween abont 1') and 1.'! "-^ of the len,uth 

 of the lio(h. in their position too, these paired tins 

 resend)le eaih other, the jiectoral fins when ex])aiided 

 being drawn down to the flat \entra! mai'gin, where 

 thev project horizontally outwards like the vcMitral fins. 

 The position of the latter is such that the distance from 

 the tip iif the snout to the foremost (outermost) j)oint 

 of their insertion is ahout 43 % of the length of the 

 hodv, and frcnn the said jioint in the insertion of these 

 fins to the corresponding point in that of the jjectorals 

 abont 2o % of the same. 



The scales are of moderate size, hut rather thin, 

 and their form varies considerably, being I'ounded and 

 quadrangular, semi-elliptical (I'ouncled behind), or round- 

 ed and triangular. In the anterior (covered) part, which 

 is the shorter, but deeper, we find only concentric, fine 

 stria'; the posterior |)art, on the other hand, is marked 

 with a number (as manj' as 24) of radiating stria;, the ends 

 of \\hich at the hind margin of the scale form fine and 

 fairh' regular notches in this margin. The lateral line is 

 fairly straight, in front slightly curved in a downward di- 

 rection, and keeps to the middle of the sides of the Ijody. 



In coloration the Gudgeon is one of the most sin- 

 gular of our Cyprinoids, not indeed for any remarkable 

 beauty of colour — though in this respect it is but 

 little inferior to our most handsome species, the Min- 

 now — but for its possession of more varied hues than 

 most of the Scandinavian forms of this family. The 

 back is graj'ish green, darker (shading into brown) oi- 

 lighter according to the colour and light of the envi- 

 ronments of the fish, and transparent when the light 

 falls directh' u|ion it. The belly is milky white. The 

 colour of tlie back extends for\vard on the top of the 

 head, the snout, and the outside of the barbels. On the 

 upper jiart of the sides of the snout, just below the 

 nostrils, appears a dark, fairly broad, longitudinal band, 

 which is continued across the upper jjart of the eye 

 more or less distinctly on the temple. Below the eye 



too, lies a more or less distinct band, formed by more 

 i or less denseh' agglomeratetl i-ollections of dark ]jig- 

 ! ment. Similar irregular spots also occur on the oper- 

 culum and preoiierculum; but the sides of the head are 

 otiierwise coated with a brassy and silvery lustre finely 

 punctated with iirowii. The lower jaw and the branch- 

 [ iostegal memiiraiK! are of thi' same colour as the bell)'. 

 The iris is below of a silvery lustre, but finely punc- 

 tated with bi-o\\ n. The silvcny lustre of the sides of 

 the b()(K shades more or less distinctly into violet, and 

 this bluish eohiui' collects at certain points intf) a nujre 

 I or less regular row of undetincHi spots above and along 

 I the lateral line, now of a lighter blue, now shading 

 even into blackish bi-o\\n. The scales of the lateral 

 line are marked, at least in the anterior part there- 

 of, liy a dense agglomeration of dark brown pigment 

 on e-M-b side of the canal itself; and more scattered 

 dots of similar pigment at the margins of the scales 

 form a network of brown o\ei- the whole body. All 

 the fins are light ami transparent, of a more or less 

 jironounced yellowish green. This last colour is most 

 prominent on the rays, which are also marked — in the 

 dorsal and caudal fin always, in the other fins some- 

 times, but with far less density — with brownish, elon- 

 gated spots, together forming more or less regular trans- 

 verse bands and most distinct on the caudal fin. 



The most trustworthy external distinction between 

 the sexes during the s]jawning-season is the dermal 

 eruption, consisting of small, tine, verrucose tubercles 

 on the head and the forepart of the back, which is 

 general among the male Cyprinoids. A dark blue s])ot 

 on the gill-cover, more prominent than in the females, 

 is also a usual characteristic of this sex during the said 

 period. Furthermore, according to Fatio, the longest 

 rays in the pectoral fins of the male are thickened during 

 the spawning-season; but we have failed to find any evi- 

 dense of this. The most general difference between the 

 sexes lies, however, in the longer and higher fins of the 

 males; but the changes of growth — young specimens 

 of both sexes being similar in this respect — impair the 

 validity of the sexual characters drawn from this rela- 

 tion. We have, however, found one of these characters 

 to hold good in all our specimens: in all the males 

 the length of the lower jaw is less, in the females 

 more, than ").') % of the length of the ventral fins". 



" The position of tlie vent, which in other cases gives tlie most easily expressed sexual character, and wliicli has lieeii stated in (lie 

 Gudgeon to lie in the females behind, in the males in front of, the middle of the body, varies so considerably that in a male 107 mm. long 

 for example we found tlie distance from the vent to the tip of tlie snout to lie ')H nnn. 



