The Eggs of Birds 459 



or erratic motion of the egg that the curious scrawls and 

 blotches upon some eggs are due. The shell is deposited 

 in successive layers, and from the dim, clouded appearance 

 of many colours we judge that the pigment is often partly 

 concealed by the outermost layers of the shell. 



Fig. 363. — Nest and eggs of Skimmer, showing the remarkable variation in colour 

 of the eggs in a single nest, heightening their resemblance to pebbles or sea- 

 shells. 



Occasionally, in the eggs of birds which number only 

 two in a nest, one egg will be almost white and the other 

 coated with an abnormal density of pigment. In certain 

 species of small birds which lay four or five eggs, one egg 

 always differs remarkably from the rest. Can we not 



