VOL. III. J Natwal History of the Fa rail ones. 159 



•ers have well-defined ideas of individual rights and the impropriety 

 oi "jumping claims." Mr. Walter E. Bryant, in his Birds and 

 Eggs from the Farallon Islands/'"- suggests that the curiously pro- 

 nounced pear shape of the guillemot's o^^g is "an all-wise provision 

 * * * preventing it from rolling off of a slightly inclined plane " — 

 by which he means, I suppose, that it has been brought about by 

 natural selection. This is a very interesting observation regarding 

 the significance of the shape of the ^^%, and certainly seems to be 

 perfectly plausible. The color of the guillemot's ^^'g is no less re- 

 markable than the shape. No two individuals lay eggs exactly 

 alike ; in fact, there is probably no bird which displays so great a 

 diversit)^ with respect to color and markings as the guillemot. Still 

 more interesting: one of the eggers, a man of intelligence and 

 veracity, apparently, informed me that the same pair of birds always 

 laid the same style of an ^g%. He said that on particular isolated 

 ledges where only a single pair built he would invariably find one 

 form of marking upon the ^g%. Thus, on taking the ^gg from 

 some known spot on alternate days, he would observe it was invari- 

 ably scrawled, or from some other nook constantly unmarked white, 

 while a third cranny would yield an ^gg spotted in a particular 

 way. If this observation be true it is of considerable interest, and 

 may perhaps furnish a clue to the reason for the diversity of type 

 in the eggs. With most birds the color of the &gg varies but little 

 from the type of the species, and we may accordingly infer that the 

 particular color is of some use, and is preserved by natural selection. 

 The form of the ^gg is frequently more variable than the color, but 

 with the guillemot the reverse is the case. The shape is remarkably 

 constant, and there seems to be a good reason why it should be so. 

 But there appears to be an equally good reason why the color 

 should be variable. In nesting in great numbers close together 

 there might frequently be difficulty in keeping each pair's property 

 distinct if all the eggs were alike, but this difficulty would be entirely 

 obviated if each pair laid a different style of ^gg. Natural selec- 

 tion, then, would not tend to preserve any one type of marking, 

 but would rather encourage as great diversity as possible. If a 

 pair does always lay the same style of &gg the birds would learn 

 their own kind once for all. This would be especially useful if the 



Proc. Cal. Acad. Sci. 2d Ser. Vol. I, p. 35. 



