PL. XX. 



' > - - . , 



j'v *%'' 



\. + 

 \ 



v 



fl 



<J>o-uffe. 



FIGS. 436 437 ARCTIC TERN. FIGS. 443444 COMMON Gnu,. 



43 8 439 LITTLB TKRN. 445 HERRING GULL. 



440442 BLACK-HKADED GULL. 446 GREAT BLACK-BACKED 



FIG. 447 LESSER BLACK-BACKED GULL. 



