STICKLEBACKS. 127 



(although I have never seen him do it), 'When one 

 of the young fish shows any disposition to wander 

 from the nest, he darts after it, seizes it in his 

 mouth, and brings it back again.' 



There are three species that come into the 

 fresh-waters of British Columbia, to nest and to 



hatch their young : 



*> 



Gasterosteus serratus, the Saw-finned Stickle- 

 back (Ayres, Proc. Cal. Acad. Nat. Sc. 1855 

 p. 47). Sp. C/i. : Body entirely plated ; peduncle 

 of tail keeled; the three dorsal spines conspicu- 

 ously serrated on their edges; anterior fin a 

 little in advance of the base of the pectoral ; in- 

 sertion of ventrals in advance of the second dorsal 

 spine their own spines serrated on both edges ; 

 posterior margin of caudal somewhat hollowed. 

 The colour of the freshly- caught fish is greyish- 

 olive along the dorsal line; but on the sides, 

 particularly in the male, it shades away into an 

 iridescence, like that seen on mother- o'pearl, 

 again changing to pure silvery-white on the 

 abdomen. 



Gasterosteus Pugettii, the Puget Sound Stickle- 

 back (Grd., Proc. Acad., Nat. Sc. Phil., viii. 

 1856). Sp. Ch. : Body only in part plated, pe- 

 duncle of tail not keeled ; the three dorsal spines 

 without serrations ; the anterior one inserted 



