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BULLETIN OF THE BUREAU OF FISHERIES. 



Among the great number of specimens collected by Mr. M. C. Marsh on St. Paul Island in 1906, 

 nearly 200 small examples were obtained from a landlocked fresh-water lake and these are not so fully 

 plated as are larger examples from the same lake. Many of the Luring specimens were infested with 

 intestinal parasites. 



Eighteen different localities in Alaska, eight of which are salt water, are represented in our collection 

 of Gasterosteits. Every specimen from the salt water is fully plated. Those found in the lakes or well 

 up the streams usually have fewer plates than those taken in or near the sea, the variation being from 

 3 plates to a fully plated condition. Those in a fresh-water landlocked lake on St. Paul Island, however, 

 are fully plated. With this exception (and this lake is not strictly a fresh-water lake), our collections 

 indicate that whenever sticklebacks begin living in fresh water they begin losing their plates, and a 

 continued residence there tends to the disappearance of most of the plates. 



Fig. 23.— Gasterosteus cataphractus (Pallas). 



An examination of our specimens from various localities gives the following results: 



Hatchery Lake near Loring, 2 specimens, 6 plates; pubic plate and spines well developed, not 

 reduced. 



River connecting with side lake, Lake Karluk, 2 specimens, 4 and G plates; spines well developed; 

 pubic plate not reduced. 



Loring, G specimens, 3 plates, only 1 plate fully developed; pubic plate and spines not reduced; 

 pectorals small. 



Lake Karluk, about 20 specimens, 4 to 12 plates; pubic plate and spines not reduced. 



Loring. outlet second lake, 1 specimen, 3 plates; spines and pubic plate well developed. 



Loring, at head of bay, many small specimens, few plates; spines and pubic plates well developed. 



Heckman Lake, 4 specimens, 3 plates; spines and pubic plate well developed. 



Karluk Lake, 12 specimens, 3 to 8 plates; spines and pubic plate well developed. 



Head of Mink Arm, 77 specimens, all fully plated; pubic plate and pectoral not different from 

 fresh-water specimens. 



Admiralty Head, 1 specimen, fully plated; spines and pubic plate well developed. 



Kilisut Harbor, 13 specimens, fully plated; spines and pubic plates well developed. 



Loring, near head of Bight, 2 specimens, fully plated; spines and pubic plate well developed. 



Loring, at head of Naha Bay, 12 specimens, plates well developed; others well developed, as are 

 the spines and pubic plates. 



Kasaan Bay, 1 specimen, plates all developed. 



Head of Yes Bay. 25 specimens, fully plated. 



