194 FISHES OF THE FIRTH OF FORTH. 



the third over the point of the ventral spine ; dorsal fin commencing 

 close behind the last dorsal spine ; anal fin commencing behind the 

 vent, with a small bent spine placed in front of the base of its ante- 

 rior ray ; ventral fin composed of a strong serrated spine, placed at 

 the base of the ascending portion of the pelvic plate ; eyes large ; 

 teeth small and fine in both jaws ; none on the vomer or palatines ; 

 base of the tail square; formed by a horizontal expansion of skin 

 placed on both sides. Colour of the head, back, and sides, brown- 

 ish-grey, shaded with green ; cheeks, thoraXj and abdomen, silvery- 

 white. Number of fin rays — 

 D. 10 ; P. 10 ; V. 2 ; A. 9 ; C. 12 ; Branchial rays 3. 



It is readily distinguished by two constant characters, 

 namely, the sides armed with plates extending from the 

 base of the pectorals to the tail ; and the base of the tail 

 being square, formed by a horizontal expansion of skin on 

 both sides. 



Mr Jenyns considers this stickleback as a mere variety 

 of the preceding ones ; but, as far as my observations have 

 led me, I agree with Cuvier and Yarrell, in considering it 

 a constant and well-marked species. I have examined cai e- 

 fully several hundred, from half an inch to two inches and 

 a half in length, and in all the specimens the lateral plates 

 were constant ; nor does the square tail exist in the other 

 species, however variable the characters may be in other 

 respects. 



This species is known throughout the whole of the British 

 coast, but is found more plentiful in some situations than 

 in others. Pennant states that at Spalding, in Lincoln- 

 shire, there are, once in seven years, amazing shoals which 

 appear in the Welland, coming up the river in the form of 

 a vast column. This concourse is supposed to arise from 

 the multitudes which have been washed out of the fens by 

 the floods of several years, and which collect in deep holes, 

 till, overcharged with numbers, they are obliged to attempt 

 a change of place. The quantity may, perhaps, be con- 

 ceived from the fact, that a man employed in collecting 



