221 



207 P. dilophus. Double-crested Cormorant. 



Winter. Common. 



Genus — Sula. Gannet. 



208 S. bassana. Common Gannet. (425. a, ym. sum.) 



September. Rather rare. 



209 S. fusca. Booby Gannet. 



September. Rare. 



Family — LAKiNiE, Gulls. 

 Genus — Sterna. Tern. 



210 S. hirundo. Common Tern. (433. f. ym. y. a, e.) 



Summer visitant. Abundant. 



211 S. arctica. Arctic Tern. (436. m. a.) 



Summer visitant. Rare. I place this and the next follow- 

 ing species among our birds, on the authority of Dr. S. 

 Cabot, vrho states, in the " Proceedings of the Boston 

 Society of Natural History," that he has procured speci- 

 mens of both from the islands in Beverly Harbor, where 

 they breed. 



212 S. dougallii. Roseat Tern. 



Summer visitant. Rare. 



213 S. minuta. Least Tern. 



Summer visitant. Not common. 



Genus — Larus. Gull. 



214 L. bonapartii. Bonaparte^s Gull. (443. y. A.) 



September to May. Common. 



215 L. atricilla. Black-headed Gull. (444. m. a.) 



Autumn. Rare. 



216 L. tridactylus. Kittiwake Gull. (446. a. w.) 



Winter. Common. 



217 L. zonorhynchus. Ring-billed Gull. 



Winter, Common. 



218 L. leucopterus. White-ioinged Silvery Gull. 



Winter. Common. 



219 L. argentatus. Herring Gull. (451. a. w. e.) 



"Winter. Common. 



