FOUR-HORNED COTTUS. 
179 
though as yet we have had time to trace it only in 
Lake Wetter." It has subsequently been obtained by 
Ekstrom from Lake Wener as well' * 1 * . For the first- 
mentioned discovery we have to thank Sergeant-major 
Hall of Grenna, who in 1836 forwarded to the Royal 
Museum several specimens of this fish, taken during 
the spawning-season. The Four-horned Cottus of Lake 
Wetter differs, however, in some respects from that of 
the Baltic and the Arctic Ocean. 
The Four-horned Cottus of Lake Wetter — or 
“ simpa ”, as it is called there and very often in the 
island-belt of Stockholm — is of smaller and more 
slender shape, being at mosf about 210 mm. in length. 
The body is strewn with smaller and fewer sharp sca- 
les on the sides, and in the female is often scaleless 
below the lateral line. The eyes are large, their longi- 
tudinal diameter (see the table above) varying between 
23 and 24 % of the length of the head, whereas this 
ratio in specimens of equal size from the Baltic or the 
Arctic Ocean varies between 17 and, at most, 21 %. 
The distance between the eyes is also less, the least 
breadth of the interorbital space in the three females 
from Lake Wetter mentioned above — which are on 
an average 152*3 mm. in length — being on an aver- 
age only 76*6 % of the least depth of the tail; while 
in the other females, the average length of which is 
155*8 mm., this ratio rises on an average to 1 05 * 1 %, 
and even in the four youngest of the latter, the average 
length of which is 126*5 mm., to 95*1 %. Of the four 
protuberances on the top of the head we find only the 
rudiments, consisting of small, low, obtuse, bony spines, 
which are most often, however, furnished with several 
points, exactly as in young specimens from the Baltic. 
To judge by specimens preserved in spirits, the colour- 
ing also seems to be much paler. According to Mr. 
Hall’s account this variety is common in Lake Wetter, 
and spawns there in November, in deep water and on 
a clayey bottom. It is not eaten. Its food consists 
of insects and small fresh-water crustaceans, among 
which it also finds its favourite morsel, the fairly 
large Idothea entomon, also a relic of the Glacial 
Period. The contents of its stomach also show that it 
greedily devours the deposited roe of other fishes. 
Malmgren and S. Loven have proved that a, similar 
variety of the Four-horned Cottus occurs in Lake La- 
doga; and the latter has founded on this find and se- 
veral others of a like nature his brilliant theory as to 
the post-glacial history of Lake Wetter and several 
other Scandinavian lakes. They carry us back to a 
time when the Arctic Ocean extended southwards from 
the White Sea across Finland till it joined the Baltic, 
which in its turn spread westwards over the districts 
surrounding Lakes Wetter and Wener. This is his 
explanation of the fact that the Four-horned Cottus, 
together with a number of crustaceans, has become an 
inhabitant of these lakes, as a survivor from a pre- 
historic Arctic Fauna. 
On the Swedish coast of the Baltic the Four-horned 
Cottus is most common in the middle portion, especially 
in the inner island-belts of Stockholm, both the northern 
and the southern. Its range extends south at least as 
far as Gothland. It also occurs occasionally even on 
the coasts of Prussia and Pomerania 6 . In the north 
it is found along the coast of Norrland, and also in- 
habits the Gulf of Finland. Its way of life probably 
differs in no important respect from that of the Sea 
Scorpion; and both these species are often met with 
together, though the Four-horned Cottus is more strictly 
a shore-fish and apparently does not occur so far out 
at sea as the other species''. Its food seems chiefly to 
consist of the crustaceans common in the Baltic, espe- 
cially the large Idothea entomon , with which one gene- 
rally finds its stomach filled, and also of mollusks and 
insects, seldom of small fishes. The spawning-season 
occurs in November, December and January, in the 
Baltic on a stony bottom. The roe is deposited, says 
Sundevall, like that of the Perch, in one single mass; 
but this is attached to the bottom in water of some 
depth, possibly even several fathoms. In a piece of 
roe which Baron Cederstrom found in a seine, the 
young were hatched during the latter half of April. 
They were then about 11 mm. in length, and their 
external and internal organs were far more developed 
than is generally the case in the fry of other fishes. 
They swam about freely, but soon sought shelter in the 
roe from which they had emerged. 
It is during the spawning-season that most of these 
fish are taken in nets, which are called Simpndt (Cottus- 
° See Malm, 1. c. 
1 Cf. M6 bius and Heincke, ]. c. 
c Cf. Sundevall, 1. c., p. 86. 
