GOTTOIDS. 
169 
Pekay", however, had previously adopted one of the 
American fresh-water Gotti as the type of a new genus, 
Uranidea, a name which has thus an older claim to 
employment, even though this claim was dubious, so 
long as only one species of the genus was known. 
In a group so naturally connected as that of the Gotti, 
it is always convenience, the convenience needed to 
facilitate the inspection of a genus, that in the first 
place decides the necessity of its systematic division; 
and in a local fauna, where the number of species is 
no greater than, for example, in Scandinavia, this 
question loses a great part of its importance. Lutken 
has pointed out b the impossibility of maintaining the 
distinctions between these genera by the help of fixed 
characters. Fixed characters are however to be found. 
The fact that a fish lives in fresh water is in itself by 
no means a sufficient ground for its systematic isolation 
— - the River Bullhead occurs in the Baltic, and the 
Four-horned Cottus lives in the larger Swedish lakes - 
but this manner of life, probably, has set on the fresh- 
water Gotti an impress of the juvenile stages in the 
development of the others, which also attain a greater 
size than they. One apparent proof of this is the fact 
that in Lake Wetter young specimens of the Four- 
horned Cottus have a smaller head than those of the 
same age in the Baltic or the Arctic Ocean. Again, 
the River Bullhead and its relative the Alpine Bull- 
head ( Cottus poecilopus) have the smallest head of all 
the Scandinavian Gotti, and might be distinguished from 
the others by means of this character, had not the 
circumstance mentioned above caused an encroachment 
of the character of the Four-horned Cottus in this re- 
spect upon the limits of the variations of the Alpine 
Bullhead. The above-mentioned characters given by 
Girard to the fresh-water Gotti also hinge upon the 
fact that they correspond to the juvenile stages of the 
other Gotti. But the smaller size of the gape, com- 
bined with another peculiarity, the length of the base 
of the second dorsal fin, which according to our ob- 
servations is generally longer, form a constant character, 
on which we base our present adoption of the fresh- 
water Cotti as a distinct subgenus. The species which 
occur in the Scandinavian Fauna may be distinguished 
by the help of the following table: 
A: Length of the maxillary bones less than 
36 % and the length of the lower jaw 
less than 44 % of the length of the 
base of the second dorsal fin. Head 
without spines on the top or on the 
snout: ■ — Subgenus Uranidea. 
a: Length of the base of the anal fin 
less than 48 % of the distance be- 
tween this fin and the tip of the 
snout Cottus gobio. 
b: Length of the base of the anal fin 
more than 53 % of the distance be- 
tween this fin and the tip of the 
snout Cottus poecilopus. 
B: Length of the maxillary bones more 
than 38 °/o and the length of the lower 
jaw more than 50 % of the length of 
the base of the second dorsal fin. Head 
with spines on the top as well as on 
the snout: — ■ Subgenus Acantho cottus. 
1 : Least depth of the tail less than 4 1 j., 
% of the length of the body and less 
than 21 % of the base of the anal fin Cottas quadricornis. 
2: Least depth of the tail more than 
4 1 / 2 % of the length of the body and 
more than 24 % of the base of the 
second dorsal fin. 
a: Lateral line smooth, with a down- 
ward curve at the end of the 
second dorsal fin. Margins of 
the branchiostegal membranes 
united to each other by a free 
dermal flap under the isthmus. 
No dermal papillse on the upper 
jaw-bone Cottus scorpius. 
b : Lateral line spinous, without any 
visible curve in the posterior part. 
Branchiostegal membranes united 
to and separated by the isthmus. 
At least one dermal papilla on 
the posterior part of the upper 
jaw-bone : 
a: Four rays in the ventral fins Cottus bubalis. 
ft: Three ,, ,, ,, ,, ,, Cottus Lilljeborgii. 
a N. York Fn., vol. IV, Fish , p. 61. 
6 Vid. Meddel. Naturh. For. Kblivn, 1 876, p. 366. 
Scandinavian Fishes. 
22 
