Order Gavi/E. 3 



The Terns (SterninaJ have been divided by Mr. Saunders — our highest and 

 most recent authority on the Gaviae— into the following eleven genera, to which 

 fifty-one species have been referred. 



i. — Hydrochetidon, or Marsh Terns, with four species, of which three are 

 recognized as having a claim to be included in the British list. They are small 

 birds with grey plumage ; the head with no prolonged gape-plumes ; the tail 

 slightly pointed and less than half the length of the wing; the bill less than 

 twice the length of the tarsus, and their feeble feet having the long slender toes 

 only half webbed. They derive their name of Marsh-Tern from nesting in marshes, 

 on tussocks or floating vegetation. 



2. — Ge/ochelidon, or Guix-BiLLED Terns, containing but a single species (which 

 visits our shores), with a stout beak, without gape-plumes ; the tail less than half 

 the length of the wing, its outer feathers pointed and longer than the others ; 

 the tarsus exceeding the middle toe and claw in length. 



3. — Hydroprogne, containing one species only, which is a visitor to our shores, 

 with no gape-plumes ; the bill very deep and stout ; the tail less in length than 

 one third of the wing, its outer feathers being pointed and longer than the rest ; 

 and the tarsus shorter than the middle toe and claw. 



4. — Sterna, the Sea Terns, embracing thirty-three species from all parts of 

 the globe, of which seven have bred on or visited Great Britain, with no gape- 

 plumes ; the bill compressed and slender ; the tail, its outer feathers pointed and 

 exceeding the rest in length, never less than half the length of the wing, and the 

 tarsus never exceeding the length of the middle toe and its claw. 



5. — Anous, or Noddies, of which there are only two species, probably reducible 

 (on the acquisition of additional specimens from the Eastern Pacific) to one, with 

 sooty plumage and grey head ; the strong and decurved beak longer than the 

 middle toe and claw; the graduated tail, with the fourth pair of feathers from 

 the outside, exceeding the rest in length. The Noddies are essentially tropical 

 birds, but two or three individuals in their wanderings have visited our shores, 

 their visits separated by long intervals of time. 



Representatives of the above five groups nest on, or have visited the British 

 Isles ; but no species of the remaining genera have yet been recorded from 

 our area. 



6. — Phcetliusa, containing but one South American species, with no gape- 

 plumes ; the bill large, stout, and twice as long as the tarsus ; the tail shorter 

 than half the length of the wing; the webs of the feet only slightly indented. 



7. — Seena, having also only a single river-frequenting species, confined to 

 India and Malacca ; without gape-plumes ; the tail, with its outer feathers pointed 



