RICHARDSON'S SKUA. 495 



Length to end of tail 21 inches; extent of Avings42; 

 wing from flexure 13 ; tail to the tip 8f , the middle feathers 

 05- longer than the rest ; hill along the ridge 1-j^, along the 

 edge of lower mandible If ; tarsus ly% ; hind toe -^, its 

 claw -j3j ; second toe \^, its claw -^ ; third toe 1-j^, its claw 

 ■f^; fourth toe Ij, its claw -^. 



Female in Summer. — Similar to the male, Avith more 

 brown on the lower parts. 



Length to end of tail 19 inches ; extent of wings 40 ; 

 wing from flexure 12f ; tail 85^ ; bill along the ridge 1-^ ; 

 tarsus 1^ ; middle toe 1-j^, its claw ^. 



Variations. — In old birds the variations are not remark- 

 able, the tint of the upper parts being only darker or lighter, 

 and the white of the lower more or less diminished in extent 

 by greyish-brown. But great differences are observed in 

 younger birds, as will be afterwards explained. Toward 

 the end of summer the colour of the upper parts becomes 

 much faded. The quills and tail-feathers are renewed by 

 the end of August, and are then glossy, and almost black 

 toward the end ; the smaller feathers are not all renewed 

 until much later. 



Habits. — In autumn, Avhen the fry of the coalfish swarm 

 along the shores, and shoals of the sand-eel sport in the 

 waters, vast numbers of Gulls, Sea-Mews, and Terns fre- 

 quent the sandy coasts. Here, on this beach, on the 

 southern side of the Firth of Forth, let us seat ourselves, 

 for a short while, and take note of occurrences. Not having 

 the organs of time or number in trim, I can only Avrite " the 

 end of August, 1831. The wavelets chase each other in 

 undulating lines, the sunbeams glitter on the smooth surface 

 of the sea, and the gentle breeze tempers the heat of noontide. 

 The sea-birds are on wing, wheeling and hovering all around, 

 vociferous in their enjoyment, their screams mingling into 

 one harsh noise, not less pleasing for a time than the song 

 of the Lark or Blackbird. Every now and then a Tern dij>s 

 into the water, and emerges Avith a little fish in its bill. 



