20 ANDERSSON, COMPARISON OF COTTUS POECILOPUS WITH COTTUS GOBIO. 
innermost ray of the ventral fin in proportion to that of the 
fin, ete. To be able to observe more easily the differences 
due to age, sex, and form, I arranged the specimens of each 
sex in three groups — small (31—53 mm. in length), middle- 
sized (53 —68 mm. in length), and large (65—94 mm. in length), 
and then, having taken in each group the average of the 
measurements of every kind, I intercompared the averages of 
the groups in each size. 
It is these averages to which I refer in the revision of 
the different measurements, and I give here, to avoid un- 
necessary repetition, the number of the specimens in each 
group. Of OC. gobio 11 small, 11 middle-sized, and 12 large 
specimens of each sex. Of C. poecilopus: small (9 males, 
7 females), middle-sized (9 males, 6 females), large (12 males, 
8 females). 
The head. 
- — - i 
C. poecilopus. | OC. gobio. 
| 45,21 57,5) 76, ec 57,9) 75,5 
Length of the body in millimetres . . . sal saglk7gales a jail 
"JA VG, , 24 , 
set of the head in & of the length ff 24,7| 24,91 26 | 25,9) 26,4] 26,8 
OLOV SME vs on ER SG jen KE 
ä 2 | 24,5] 24,7) 24,61 26,1) 26,3] 26,6 
Length of the bister parfipt the head in 3 17,8| 17,8| 18,9] 17,9| 18,7 19:23 
Eg e length NAN oe | 
PR ÄT IA |? | 17,6 17,5] 17,7| 18,9] 18,5] 18,9 
Length of the head behind the eyes in 2 12,1|/ 12,5) 13,31 13,3) 14,4] 14 | 
of the length of the body. . «+ : sc el 149 oM dr 189 i än | 
BOREN Te the cheek in 4 of the length of > 10,4] 10,5| 10,1 11,5 3 a 80, Ga EST 
body 0 STEINS svT 5; Å NE 
"Å2 | 10,5) 10,7) 10,4] 11,2) 11,3) 11,5 
Longitudinal diameter of the eye in 4 of SA (SR 9 3 1 
the length of the body . . . . .. sd sta al jer - + I pe 
| 221 14 Jar , , 7 | 
or bn rg snout in 2 of the length se 6,5|"6;7| Tal] "TA 7,6] 
EEE SR VIL Nr, EEE I I I 
21 6,5) 6;6) 6,9) TING 
Breadth of the interorbital space in 4 of gl Ta SA 
the length of.;the body ia co cfolld sfers JT av ps Aly Et js 
lo | 2,6) 2,8| 28) 28) 27 34 
ir NOA the head in 4 of the 5 16,2) 17,8] 19,5 19,0] 21,31 22,2/ 
röntga " "Åo | 17,6|18,5| 19,1] 18,1/ 21,0] 21,5 
frebtosk hejeht jan the head in 2 of DN ped 13,3| 14,6) 15,31 14,1] 14,71 15,5 
R Zn vn [9 113,9) 14,8] 14,4] 14,2] 14,7) 15 
