THE DUCK HAWK, ETC. 159 



of white ground color. About the middle of the egg the 

 colors are in more equal proportions, the white patches 

 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 Pere- 

 grine's eggs 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. 







L ; gth. 



Trop of breadth 

 Breadth. to length. 



Point of greatest transverse 

 diameter from small end. 



No. 1 





2.18 in. 



1.71 in.. 0.785 



0.640 r 



gth of the egg 



" 2 





2.21 " 



1.67 " 0.756 



0.540 



<t 



" 3 





2.32 " 



1.70 " 0.732 



0.656 



a 



" 4 





2.16 " 



1.65 " 0.765 



0.600 



a 



Average 





2.22 " 



1.68 " 0.759 



0.609 



a 



Greater extr. 





2.32 " 



1.71 " 0.785 



0.656 



a 



Lesser extr. 





2.16 " 



1.6.5 li 0.732 



0.540 



l< 



Am't of variation 



0,16 " 



0.06 " 0.053 



0.116 



a 



Dr. Brewer's 



spec. 



2.00 " 



1.56 " 0.780 







From the above table it will be seen that the range of 

 variation in the four specimens in length is .16 of an inch; 

 or nearly seven and 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 proportion ; the varia- 

 tion in the position of the point of greatest tranverse 

 diameter is about eleven and a half per cent, of the whole 

 length of the Qgg, the form of the eggs varying from an 

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



