14 Brit is Ji Birds ^ 



ence in size between diiferent specimens of what are 

 in reality eggs of tiie same species of birds, but seem 

 to him, from their discrepancy of dimensions, not 

 possibly so. 



Again, the colour and markings of many different 

 species of eggs are found to admit of great variation. 

 The most familiar and striking instance is in the case of 

 the Guillemot; but one more within the reach of every 

 nest-hunter is presented by the eggs of the Blackbird. 

 Sometimes the spots on them are very minute and 

 multitudinous ; almost confluent from their number 

 and minuteness ; sometimes large and well-defined 

 and permitting the ground-shade of the shell to be 

 very apparent; sometimes reddish in colour, closely 

 approaching the shade of those on the Ring Ousel's 

 eo^o', and sometimes brown in hue, with no reddish 

 tinge at all ; and sometimes they disappear altogether, 

 or very nearly, and leave the ^gg with a strong 

 resemblance to the little-spotted Thrush's ^gg?- To 

 such an extent is this the case, that a year or two 

 since I was misled into assuming that four eggs 

 which I found in a nest with all the characters of a 

 Blackbird's nest, must most certainly, from their 

 colour and markings, be assigned to a Thrush original 

 and not to a Blackbird. Other familiar instances of 

 the same kind may be noticed as met with in the 

 House Sparrow, the Tree Pipit, the Sky Lark, the 

 Yellow Hammer, one or more of the Hawks, etc. 



In the fabric and materials of nests, again, as con- 

 structed by birds of the same species, much dissimi- 

 larity, under peculiar circumstances, will be found to 

 1 Yarrell, i. 204. Ilewitson, i. G3. 



