BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 24. AFD. IV. N:08. 33 
It is clear, however, that the ray increases in length in 
C. gobio, this being most noticeable in the males: in the 
males of OC. poecilopus the fin also grows, but only very 
slightly, and diminishes very much in the females. 
In the original common type this ray was probably of 
medium length. At a later period, when the two forms se- 
parated, the ray continued its growth in C. gobio, while in 
the other form it checked in its development. Later on in 
the female this check became a distinct decrease. In the 
male the tendency to decrease in the ray came into conflict 
with that to increase in the whole fin, which explains the 
aberrant course of development. This slight increase in the 
poecilopus-males may probably at a later period become a 
decrease, to which also the development of the ray in the 
females would contribute. 
In the preceding observations we have usually found 
that the two forms developed in the same direction, although 
sometimes the one sometimes the other has advanced farther, 
for which reason we may say tbat sometimes the one some- 
times the other remained in a more primitive stage. We 
find, however, a case of the opposite in this respect, as re- 
gards the length of the anal fin compared with its distance 
from the tip of the snout, the two forms following in their 
development from the common starting point divergent courses 
or more correctly speaking quite opposite ones, and this na- 
turally caused constant differences to appear much sooner 
than the other course of development would have done. 
The distance of the dorsal fins from the tip of the snout. 
C. poecilopus. || OC. gobio. 
Ha 
bd 
Nn 
vt 
DE 
Sn 
[a 
0 VO LRA 
Distance of the 1st dorsal fin from the tip [3] 26,4 
of the snout in 4 of the length of the body 19 26.9 
Distance of the 2nd dorsal fin from the tip [341,34 
of the snout in 24 of the length of the body 12 42.9 
5| 76,1 42,5] 57,9| 75,5 
| 76,11 42,41 58 | 75,8 
| 27,7) 28,11 29,11 29,6 
26,8|| 28,9) 29,2[ 28,9 
21 44 41 42,8) 44 144,8 
43,6 | 42,3) 44,3) 44,7 
Length of the body in millimetres . 
I 
ND 
NM 
ND MD 
ND 
NN & 
Ha 
2» 
[CS 
> 
The distances from the tip of the snout increase with 
age in the two forms, together with the size of the head 
3 
