26 



ance with its local surroundings and can have no fixed scale of variation^ 

 the egg, equally with the bird, must have a fixed and uniform scale of 

 variation in accordance with the latitude or altitude at which it is found, 

 most particularly in size and measurements. 



The following table of accurately measured specimens actually collected 

 in the sections named, gives what I believe to be fairly accurate av- 

 erages, and a surprisingly uniform scale of gradation in size from South 

 to North and from East to West in the Humid Province. Owing to the 

 small amount of data at hand, I am unable to trace an unbroken line of 

 variation in the Arid Province ; but from that at my disposal I find 

 the minimum to be on the coast of California, and the maximum in the 

 south-western portion of Washington, with Colorado between. This- 

 increase or decrease in measurements in different localities needs no other 

 explanation than that which has already been given as the probable cause 

 of the increase or decrease of the number of eggs in a set ; which is 

 too well known to all ornithologists to warrant further comment. 



MEASUREMENTS. 



LOCALITY. 



North Carolina 



Pennsylvania 



New York 



New England 



O., Ind., S. Mich 



ill, S. Wis., la 



Minn., N. Da., Mana. 



California 



Colorado 



Washington 



NO. OF EGGS 



MEASURED. 



27 



225 



320 



97 



44 



132 



35 

 29 



17 

 14 



1.73 X 1.26 

 2 . 06 X 1 . 1 2 

 2.03x1.33 

 1 . 86 X 1 . 40 

 1.79X 1. 19 

 1.95 X 1.27 

 1 . 94 X 1 . 40 

 1.78 X 1. 16 

 1.72 X 1. 14 

 1.83 X 1. 19 



INIMUM. AVERAGE. 



48 X 1.08 1.62 X 1. 14. 



42 X 1.05 1.64 X 1. 15 



43 X 1.08 1.65 X 1. 15 

 43 X 1. 1 2 1.66 X 1. 17 

 55 X 1. 10 1.68 X 1. 17 

 51 X 1. 13 1.68 X 1. 18 

 55x1.17 1.73x1.27 

 48 X 1.03 1. 61 X 1. 13 



59x1.13 1.63x1.15 



64 XI. 12 I.7IXI.18 



Maryland. Tennessee, Mis- 



n number that the averages 



no 



I also have measurements from Ontario, 

 souri, Kansas, and Nebraska, but so few 



could not be that of the localities named, and therefore can hav 

 bearing on the subject. It is safe to make the assertion that there is an 

 increase of about one-hundredth of an inch in the measurements of the 

 average egg, corresponding to an increase of about two and one-half de- 

 grees in latitude or its equivolent in altitude. The increase from East tO' 

 West is not so pronounced nor constant yet the data at hand shows an 

 average increase of one-hundredth of an inch to a corresponding increase 

 of four degrees of longitude from the Atlantic seaboard to the western 

 limits of the Humid Province. The surprisingly great difference be- 

 tween the maximum and minimum eggs (.64X.35) leads one to speculate 

 on the probable number of eggs of Corvns americamis to be found in 

 certain of the innumerable (x>logical collections, masquerading under the 



