BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 24, AFD. IV. N:0:8. dl 
As shown in the above table the paired fins are about 
equal in length in the two forms, this being especially no- 
ticeable in the ventral fins, which are of almost exactly si- 
milar length in the two, except in the full-grown males. In 
these the ventral fins of C. poecilopus are, as shown above, 
considerably elongated, this being a sexual character, in which 
C. poecilopus corresponds with a fairly large number of ma- 
rine Cotti. This character is probably rather primitive, though 
strangely enough it is totally wanting in C. gobio. A sug- 
gestion of the same appears also in the somewhat larger size 
of the pectoral fins in the males of C. poecilopus. 
The correspondence between the two forms is not, how- 
ever, confined to the length alone; there also exists great 
similarity in the course of their development. In the males 
the fins always increase slightly in OC. gobio but more in 
C. poecilopus. In the females they increase in length at first 
but decrease again considerably in the pectorals, slightly or 
not at all in the ventral fins. 
The number of the rays in the pectorals is usually 14; 
in the ventrals I found one spinous ray and four articulated 
in all my specimens, except in one of C. poecilopus, in which 
the innermost small ray was wanting on one side of the fish.! 
In the pectorals the rays vary in number, these being very 
often 13, sometimes 15 and very seldom so few as 12, which 
last number I found in one fin of each of three specimens 
out of 120 (1 C. gobio and 2 C. poecilopus). We very often 
find specimens with one more ray in one of their pectoral 
fins than in the other: I only once found one with two rays 
more. In regard to the number of rays there is no difference 
to be detected between the two forms nor between the sexes. 
The different branching in the fin-rays has been spoken of 
above. 
These fins, then, are in the two forms developed in pa- 
rallel lines, in the direction which the primitive type pro- 
bably began to take at an early period. In this original 
1 FATIOo mentions that sometimes C. gobio has only two or three arti- 
culated rays in the ventral fins. The French writers on the subject, whom 
GÖNTHER followed in his characterization of the French form in »Die Fische 
des Neckars>, generally say that C. gobio has always three articulated rays 
only. According to FaATtio this may have been because these authors did not 
notice that the outermost ray in reality is composed of two such (the spinougs 
and one articulated). 
