THE TEN-SPINED STICKLEBACK 249 



repairs every damage to the nest and often renews 

 the water by placing himself in front of the opening 

 and vibrating his pectoral fins. When the eggs 

 hatch out he destroys the nests, leaving only the 

 foundations as a sort of cradle, which he continues 

 to guard ; as the young gain in size and strength 

 they try to leave the nest, but are always intercepted 

 by the father, who takes them in his mouth and 

 returns them to their quarters. At last his care 

 begins to slacken, and finally they are left to shift 

 for themselves. 



THE TEN-SIGNED STICKLEBACK or TINKER 

 (Pygosteus pungitius) differs from the preceding 



FlG. 23. Ten-spined Stickleback. 



species especially in the more numerous dorsal fin- 

 spines, which vary in number from seven to twelve, 

 and are alternately divergent to the right or left, 

 and in the wider gill-openings, which are confluent 

 below. It is a smaller fish than the Three-spined 

 Stickleback, attaining a maximum length of 3 inches. 

 It has nearly the same geographical distribution as 

 the Three-spined Stickleback, but does not extend 

 so far south, in Europe not crossing the Alps ; in our 

 islands there are no reliable records from Scotland 

 north of Loch Lomond and the Forth. 



Except in the far north the Ten-spined Stickle- 

 back is principally a freshwater fish, but is found in 

 the Baltic ; until a study has been made of a much 



