FISHES. 479 



being equal only to one-third of an eye diameter. 

 Colour bright red ; much paler on the belly than the 

 sides,, with three indistinct dark bands. The largest 

 specimen seen by Nilsson was taken off Bergen, and 

 was 14 in. long. D. 12,13; P. 19; V.1,5; A. 3,5; C.13. 



Gen. Gasterosteus, L. 



Small dull-looking fish, living as well in salt as fresh 

 water ; head and body much compressed ; head with spines 

 or tubercles ; body covered more or less with shield-like 

 plates ; several free sharp spines on the back, instead of a 

 first dorsal ; ventrals reduced to a single spine. 



21. GASTEEOSTEUS ACULEATUS, L. Tretaggad Spigg. The 



Three-spined Stickle-back. D. F. 

 Assuming, as I believe is now the general opinion, 

 that the rough-tailed stickle-back (G. trachurus } Cuv.), 

 the half- armed stickle-back (G. gymnurus, Cuv.), and 

 the short-spined stickle-back (G. brachycentrus, Cuv.), 

 are nothing more than three varieties of the common 

 three-spined stickle-back (G. aculeatus, L.), we may 

 observe that one or other form is met with in most of 

 the Scandinavian waters, both brackish and fresh, from 

 the very south of Sweden up to far within the Polar 

 circle. They appear to assume their red marital colour- 

 ing in May, are in high colour in the end of June, and 

 even in the beginning of August. The usual length here 

 2 in. Three free rays on the back. D. 12 ; P. 10 ; A 1,8. 



22. G. PUNGITIUS, L. Tio Taggad Spigg. The Ten-spined 



Stickle-back. D. F. 



Is as generally dispersed in these waters as the last, 

 with which it associates, but is no where so common. 

 Usual length 1^ to 2 in. 



Noticing Mr. Newman's remarks on the Scandinavian 

 species (quoted by Couch), and which, as Newman properly 

 observes, is figured by Bkstrom in his magnificent work on 

 the Scandinavian fishes, ' ' with only nine spines on the back, 

 and with a red colour on the gills and breast/' I may add, 



