l'ii|l!-llilKNKI) col TIS. 



179 



though as yet wo liave liad time to trace it oiil\- in 

 Lake Wetter." It lias subsequently I)eeM ol)taiiie(l l)y 

 Ekstrum from Lake Wener as well". For tlie lirst- 

 meutiouefl diseover}- we lia\e to tliank Sergeant-major 

 H.\LL of (Ireiuia, wlio in 18;^>(i forwarded to the Ko\'al 

 Museum several s]H'cimens of this Hsh, taken during 

 the spawning-season. The Four-homed Cottus of Lake 

 Wetter dirt'ers, however, in some respects from that of 

 the Baltic and the Arctic Ocean. 



The Four-horned ('ottus of Lake Wetter — or 

 ''siiiipn", as it is called there and verv often in tlic 

 island-lielt of Stockholm — is of smaller and more 

 slender shape, hcing at most -about 210 mm. in length. 

 The body is strewn with smaller and fewer sliarp sca- 

 les oil 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 96 of the length of the head, whereas this 

 ratio in specimens of ecpial size from the BaJtie or the 

 Arctic Ocean varies lietween 17 and, at most, 21 %. 

 The distance lietween the eyes is also less, the least 

 Iji'cadth 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 ?«i of the least depth of the tail; while 

 in the other females, the average length of which is 

 15.')'8 mm., this ratio rises on an average to 105'1 %, 

 and even in the four youngest of the latter, the average ' 

 length of which is 126"5 mm., to 95' 1 ?4. ()t the four 

 protuberances on the top of the head we find only the I 

 rudiments, consisting of small, low, obtuse, bony sjiines, 

 wiiich 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-^vater crustaceans, among 

 which it also finds its favourite morsel, the fairly 

 large Idothca ciitoiiion, also a relic of the Glacial \ 

 Period. The contents of its stomach also show that it 

 greedily devours tlie deposited roe of other fishes. 

 Malmgken and S. Lovex have proved that a similar 



variety of the Four-liorned Cottus occurs in Lake La- 

 doga; and the hitter has founded on this find and se- 

 veral others of a like nature his lirilliant theory as to 

 the post-glacial liislory of Lake Wetter and several 

 other Scandinavian lakes. Tlie\- carr\- us back to a 

 time when the Arctic Ocean extended southwards from 

 the White Sea aci-oss Finland till it joined the Bjaltic, 

 which in its turn spread westwards o\ci- the districts 

 surrounding Lakes Wetter and Wencr. This is his 

 explanation of the fact thai (he Foiir-hoi'iied ('ottus, 

 together with a number of ciaistaceans, has become an 

 inhabitant of these lakes, as a sur\i\or from a pre- 

 historic Arctic Fauna. 



< )n the Swedish coast of the Baltic the Four-horned 

 Cottus is most common in tiie 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 Pomei'ania*. 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 

 Scor]>ion; and both these species are often met with 

 together, though the Foui'-horned Cottus is more strictly 

 a shore-fish and a])parently 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 Idothca cnfomon, with which one gene- 

 rally finds its stomach tilled, 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 Cederstkom found in a seine, the 

 young were hatched during the latter half of April. 

 They were then about 1 1 mm. in length, and their 

 external and internal organs were far more developed 

 than is generally the 'case in the frv of other fishes. 

 The-\" swam about freel\-, 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 Sinqtiu'if (Cottus- 



" See Malm, 1. c. 



* Cf. MoBius am\ Heixcki:, 1. c. 



' Cf. SUNDEVALL, 1. C, p. 8(5. 



