BRITISH LARIDM 337 



The first (the Sterninse) includes the several 

 varieties of tern, the characteristics of which are 

 the small size of the legs and feet, and the length 

 of bill, which eq2ials or exceeds that of the head. 



The second (the Larina^) are characterized by 

 the strength and size of their legs and feet, their 

 bills being shorter than their heads. This sub- 

 division includes the different varieties of the gull. 



The third (the Stercorariinse) are recognizable 

 by their having the upper mandible hooked at 

 the point, its base being covered with a skin. 

 This subdivision includes the four varieties of the 

 skua, the ' robber gulls/ as they are termed. 



In the Larina^ we have no fewer than thirteen 

 varieties, varying in length from eight and a half 

 to twenty-one inches : 



1. The black tern. 8. The Arctic tern. 



2. The white - winged 9. The common tern. 



black tern. 10. The little tern. 



3. The whiskered tern. n. The sooty tern. 



4. The gull-billed tern. 12. The lesser sooty 



5. The Caspian tern. tern. 



6. The Sandwich tern. 13. The noddy tern. 



7. The roseate tern. 



Of these thirteen, six are either rare or too un- 

 common to refer to, viz. : 



The whiskered tern The sooty tern. 



(very rare). The lesser sooty tern. 



The gull-billed tern. The noddy tern. 

 The Caspian tern. 



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