260 THE ZOOLOGIST. 



deposited among the rufous-tinted shingle were of a russet- 

 colour. The ground here was as smooth almost as if it had 

 been rolled ; indeed, the levelled stones gave one the impression 

 of a rude attempt at tessellated pavement. Among the blue- 

 grey patches of pebbles the predominating tints were greyish, 

 and on the greener portions they most assimilatively assumed 

 that coloration. In some instances, however, protective colouring 

 was a negative quality, and conspicuously contrasted eggs quickly 

 caught the eye. Dr. Long pointed out one egg, on a dark ground, 

 of a vivid bluish green, and some nests contained three differ- 

 ently coloured eggs. Every egg was blotched more or less with 

 bluish ash and dark brown. 



The eggs of the Common Tern were easily distinguished from 

 those of its confrere by their larger size. In almost every in- 

 stance three eggs were laid, and most were hard-set ; I obtained 

 an addled one of each species, and understood that one clutch of 

 young birds had already forsaken their nest. We looked in vain, 

 however, for any of them in the adjacent marrams ; they appear 

 to be as capable of concealment as the little ones of the Ringed 

 Plover. Extreme vigilance was necessary to avoid trampling on 

 nests, but we soon learned to "spot" them, thanks to Tom 

 Cringle's "trade mark" in the shape of a heel-pushed heap 

 about a foot away from each one. With a few exceptions every 

 nest of the Common Tern was lined with coarse, sixpenny- sized 

 pieces of Cockle and Oyster shells, those of the Little Terns 

 being adorned by a handful of finer fragments. There can be 

 no doubt these pieces of shell are collected by the birds in- 

 stinctively for the sake of their useful retention of heat ; they 

 certainly do not add to the comfort otherwise. All the eggs were 

 not only warm to the touch, but the lining of shells was dis- 

 tinctly so also. Their Ring-Plover neighbours used still smaller 

 fragments. A few of the larger Terns' nests were lined with dry 

 grass-bents, and formed really comfortable cosy habitations. 



Here and there we came across patches of pebbles running 

 larger, many of the size of the Terns' eggs, others up to that of 

 a hen's egg ; these seemed to be seldom wetted, even by the sea- 

 spray, and were of a blue-grey colour ; many of them were 

 plentifully spotted with a minute lichen, which I have been 

 referred to as Lecanora aspersa, and also as Lecidea petrcea, the 



