43 



Obs. 2. 



In the Common Brown Owl (^Syrnium Aluco). 



Long Diameter. Short Diameter. 



1-2000 1-4000 



1-1895 13555 



1-1777 1-5333 



1-2400 1-3000 



1-1714 



1-3801 



1-1930 



Obs. 3. 



In the Passenger Pigeon (Colmnba migratoria). 



Long Diameter. Short Diameter. 



1-2133 1-4800 



1-2000 1-4570 



1-1895 1-5333 



1-1777 1-4000 



11714 



1-2666 1-4626 

 1-1542 



1-1909 



Obs. 4. 



In the Russet Pigeon (Columha rufina). 



Long Diameter. Short Diameter. 



1-2400 1-3428 



1-2286 1-4000 



1-2666 1-3000 



1-2000 



1-3429 



1-2314 



" From the observations on the blood corpuscles of the Snowy Owl, 

 it results that their average long diameter is l-1550th, and their 

 average short diameter 1 -4042nd of an inch, so that their length is 

 considerably above twice and a half greater than their breadth ; while 

 in the Brown Owl the corpuscles are scarcely twice as long as they 

 are broad. 



" Now both the absolute size of the latter, as well as the relation 

 between their long and short diameters, approach very nearly to the 

 dimensions frequently presented by the corpuscles of various birds. 

 But in the Snowy Owl the corpuscles are not only peculiarly long, 

 in proportion to their breadth, but their absolute length is much 

 greater than is often to be found in the red particles of other birds, 

 whether belonging to the rapacious order or not. Indeed it is pro- 

 bable that the difference generally between the blood-disks of any 



