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. Se. 1855 
p. 47).—Sp. Ch.: 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 Pugettit, 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 
