51. The Common Stickleback. Gasterosteus aculeatus. 



Length, four inches. Color, back, olive, dotted; sides, silvery. Three spines on back, two of them being 

 before the fin ; also one spine in hind belly fin. 



Lives along the shore at the mouth of brooks and rivers. 



52. The Black Stickleback. Gasterosteus wheatlandi. 

 Three spines connected with the back fin. 



53. The Slender Stickleback. Gaterosteus atkinsii. 

 Length, one and one-half inches. Three spines connected with the back fin. 

 Lives on the Maine coast. 



54. The Four-Spined Stickleback. Apetta quadrants, 



Length, two inches. Color, dark olive, mottled ; belly fins, red. Four spines in back fin and one in hind 

 belly fin. 



55. The Brook Stickleback. Eucalia inconstans. 

 Length, two and one-half inches. Color, black with red tints. Five spines on back and one in lower hind fin. 



56. The Nine-Spined Stickleback. Pygosteus pungitius. 



Length, two and one-half inches. Color, olive, spotted and striped with black. Ten spines on back and one 

 in lower hind fin. 



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