286 



Revised Arrangement of the Ornithological System of Cuvier 

 and Dumerily with reference only to the Genera and Species 

 of the British Islands. 



Birds are vertebral and oviparous animals, with lungs and 

 warm blood, producing their young enveloped in a calcareous 

 shell, requiring a heat of 100° Fahrenheit to mature their for- 

 mation. In other respects there is a great analogy with the 

 mammiferous class of animals. 



Their bones are generally hollow, containing air ; their lungs 

 are attached to the ribs, perforated externally, by which this 

 fluid is distributed through every part of the body, but chiefly 

 into two large membranaceous vessels, or sacs, situated in the 

 thorax and abdomen, by which the body is much enlarged, and 

 rendered considerably lighter. This provision of air affords, 

 in some degree, an additional power of respiration and vigour. 

 It is even supposed that the increased temperature which 

 birds acquire during incubation, and the extensive flights they 

 are enabled to undertake in their periodical migrations, depend 

 much upon the action of air on the blood. It has been ascer- 

 tained that two sparrows consumed, in a given time, as much 

 air as a guinea-pig. 



They sleep resting on one foot, the weight of the body being 

 sufficient to act upon a series of muscles, extending through 

 the thigh to the extremity of the toes, which, in proportion to 

 the pressure of the body, contract and adhere to the perch on 

 which they rest. 



The neck is amply supplied with vertebrae moving in all direc- 

 tions, but in the back-bone they are connected and motionless. 



The breast-bone, with which the muscles of the wings are 

 connected, is of considerable size and strength; it is composed 

 of five parts ; the degree of ossification in the posterior lateral 

 pieces is proportioned to the power of flight in each species. 



The wing is divided into three principal parts, — the shoulder 

 (brachiumjf the arm (cubitus), the hand (carpus). The fea- 

 thers on the hand are always ten in number, called Primary; 

 those on the arm. Secondary; those on the shoulder, Scapu- 

 lary ; those on a small projection from the hand form what is 

 tailed the bastard wing. 



