brooks: birds from east Siberia and arctic Alaska. 373 



Mr. Dixon took several specimens at Humphrey Point during the 

 early part of June. 



One immature bird was taken at East Cape, August 29, 1914. 



Larus ridibundus Linne. 



A few were seen at the head of Avatcha Bay, during the second 

 week of May. The collection contains a male taken at Copper Island, 

 May 22, — , purchased. 



Larus schistisagus Stejneger. 



SLATY-BACKED GULL. 



A few were seen in Avatcha Bay during second week in May and 

 about Cape Shipunski where a male was taken May 21, 1913. 



Larus brachyrhynchus Richardson. 



SHORT-BILLED GULL. 



Several gulls were seen on Demarcation Bay, Alaska, July 18, 1914, 

 that I referred to this species. No specimens were taken. 



Larus glaucescens Naumann. 



GLAUCOUS-WINGED GULL. 



We found this species breeding at St. Lawrence Island, and Provi- 

 dence Bay, eggs taken June 20 at St. Lawrence Island being very 

 advanced in incubation. 



A female taken at Copper Island, May 22, is in the purchased 

 collection. 



Larus tilyyeri, sp. no v. 



Thayer's gull. 



I take great pleasure in dedicating this interesting species to Col. 

 John E. Thayer whose enthusiasm and generosity have greatly en- 

 riched the collections of the Museum of Comparative Zoology. 



