THEIR REPRODUCTION (EGGS) 281 



egg. In some groups this is much more fre- 

 quent than in others, as, for instance, amongst 

 the Birds of Prey and Terns and Gulls. The 

 ground-colour in the eggs of such species that 

 display it appears to be deposited soon after the 

 first set of spots are distributed ; in Game Birds 

 the deposition of spots and ground-colour may 

 be almost simultaneous. The amount of colour- 

 ing matter deposited is remarkably uniform in 

 the various species, generally speaking, especially 

 as regards the ground tint. Its arrangement, 

 however, is so diverse that probably no two 

 eggs are exactly alike, although they present 

 certain characteristics that render identification 

 a fairly easy task. As a rule, the eggs in a 

 clutch resemble each other ; and in many cases 

 we know that this resemblance keeps constant 

 through successive clutches laid by the same 

 parent ; possibly the similarity may exist per- 

 manently during the life of the producer. Most 

 collectors have had experience of this fact, 

 obtaining certain peculiarly marked eggs from 

 certain spots for several seasons in succession. 

 This extends not only to eggs of the normal 

 colour, but to others displaying certain peculi- 

 arities of markings, or even the want of them. 

 ' In some species it is almost an invariable rule 



