1865.] Dr. Davy on the Temperature, fyc., of Birds. 44-7 



rience the same exemption ; why one bird, the apteryx, a solitary example 

 should be without air not only in every part of its osseous system, but also 

 without air-sacs ; and another bird, the grouse, not remarkable for power 

 of flight, should have air in its femora as well as humeri, are questions 

 which at present it may be difficult to answer, but which, it may be hoped, 

 were careful and minute inquiry instituted, might be satisfactorily accounted 

 for on the teleological principle of fitness of structure to use. 



If I may be allowed to offer a conjecture, it seems to me probable that 

 in our commonly received generalization relative to the consumption of 

 oxygen in the respiration of birds, the quantity presumed to be used has 

 been overrated, and that in many instances the expenditure of this gas may 

 be found to be less proportionally than in the mammalia. 



As supplementary to the preceding observations, I would beg to state 

 some further particulars respecting birds, the results of the inquiry in 

 which I have been engaged. 



1st. Of the birds examined. All of them were natives of the Lake Dis- 

 trict, with two or three exceptions which will be specified, and all were 

 obtained between November and March, excepting those marked with an 

 asterisk, which were shot in April and May, They may be divided into 

 two sections, one including those birds in one or more of the bones of 

 which air was found to exist communicating with the lungs. The other, 

 of those birds in which in the corresponding bones no air could be detected. 

 The birds were all at least one year old, an ample time, I apprehend, for 

 the marrow which exists probably in the bones of every individual of the 

 class at the time of hatching, and for some time after, to be absorbed in 

 those in which it is not permanently present. 



It may be right to remark that in every instance the question whether 

 air was present or not was determined bv an examination of the contents 

 of the particular bones, and not merely from their appearance, which, as 

 regards colour, is sometimes deceptive. 



Of the birds belonging to the first section, the bones, which are named 

 after each, were those only in which air was found, i. e. communicating 

 with the lungs. 



SECTION I. 



Buzzard (Falco buteo) humeri, scapulae, clavicles, furcula, femora. 



Tawny owl (Strix stridula) do. do. do. do. do. 



Carrion crow ( Corvus corone) do. do. do. do. 



Rook (C.frugilegus) . do. do. do. do. 



Jackdaw (G. monedula) do. do. do. do. 



Magpie (G. pica) do. do. do. do. 



Jay (G. glandarius) do. do. do. do. 



Cuckoo (Cuculus canorus) do. 



Common fowl (Gallus domesticus) do. 



Pheasant (Phasianus colchicus) do. 



