14 ORNITHOLOGY AND OOLOGY. 



becoming larger on the smaller end towards the middle, and the 

 red patches on the larger end increase towards the same point, 

 where the colors meet and become mixed in irregular patches of 

 various sizes, from mere dots to blotches. The smaller end has a 

 few streaks and blotches of dark-purple overlying apparently the 

 other colors, as in specimen No. 1. 



" These specimens are very interesting, as indicating the great 

 amount of variation to which the American Peregrine's egus are 

 subject ; and especially so since they are all the product of one pair 

 of birds, laid in one set, and identified as such beyond question. 

 In coloration, a transition can be traced between the extreme in the 

 order they are numbered, which is undoubtedly the order in which 

 they were laid, as indicated by the thickness of the shell as well as 

 by the depth of color. 



TABLE OF COMPARATIVE MEASUREMENTS. 

 Length. 



No. 1 2.18 in. 



No. 2 2.21 „ 



No. 3 2.32 „ 



No. 4 2.16 „ 



Average 2.22 „ 



Greater extreme . . . 2.32 „ 



Lef-ser extreme . . . 2.16 „ 



Amount of variation . 0.16 „ 



Dr. Brewer's specimen . 2.00 „ 



" From the above table, it will be seen that the range of varia- 

 tion in the four specimens in length is .16 of an inch, or nearly 

 seven and a half per cent of the average length; in breadth, .06 

 of an inch, or about three and a half per cent of the average 

 breadth : in the proportion of breadth to length, about fifteen per 

 cent of the length, or nearly twenty per cent of the average pro- 

 portion. The variation in the position of the point of greatest 

 transverse diameter is about eleven and a half per cent of the 

 whole length of the egg ; the form of the eggs varying from an 

 ellipsoid in No. 2 to an ovoid, which, in No. 3, has the smaller end 

 considerably elongated. It will be observed that the egg meas- 

 ured by Dr. Brewer is considerably smaller than my smallest 

 specimen, and that the proportion of breadth to length scarcely 

 differs from the same proportion in No. 1. 



