SOOTY TERN. 565 



a bird often found breeding in the same localities in which 

 the shell is of a rough calcareous nature. The yolk of the 

 egg of the Sooty Tern is of a rich saffron -yellow. 



As soon as the young can fly, both they and their parents 

 go away to sea. Their power of sustained flight is very 

 great, and even when catering for the young the old birds 

 must travel great distances, for Mr. Gill caught a bird with 

 his hand, with a small fish in its beak of a species quite 

 foreign to Ascension waters. 



In the adult the beak is black ; the forehead white, ending 

 in a concave curve with a point over each eye ; a black streak 

 from the base of the bill to the eye ; top and sides of the head, 

 occiput and nape, black ; upper surface of the body and wings 

 brownish sooty-black ; tail deeply forked, of the same dark 

 colour as the back, except the outer webs and basal portions of 

 the outside tail-feathers, which are white ; chin, cheeks, sides 

 and front of the neck, breast, belly, under surface of the 

 wings, under parts of the body, under tail-coverts, and base 

 of the tail-feathers, white ; under surface of the lengthened 

 portion of the tail-feathers ash-grey ; legs, toes, and inter- 

 digital membranes, which extend to the extremities, black. 

 The whole length of the bird is about sixteen inches ; wing, 

 from flexure, eleven inches. In birds which are not fully 

 adult the outer webs of the long tail-feathers are more or 

 less umber-brown. 



In the immature bird the plumage is of a nearly uniform 

 sooty-brown, lighter on the under wing- coverts ; and the 

 feathers of the upper parts are tipped with white ; bill and 

 legs dark brown. The young in down, of a few days old, 

 is brownish-grey above and white on the under parts ; but 

 brown feathers soon make their appearance on the flanks, and 

 extend over the entire breast and abdomen ; the feathers of 

 the back are then blackish-brown, broadly tipped with white. 



THE SMA.LLEK SOOTY TEEN, Sterna ancestheta, Scopoli, 

 frequently known as Sterna panayensis, is believed by the 

 Editor to have straggled to one of the lightships at the 

 mouth of the Thames, in September 1875. Both Mr. Bid- 



