4 



ALCA. 



the second nearly half as long- as the third, which is the longest. The 

 hedge-chanter ( A. modularis ) is the only British species of the genus.* 



ACCIPITER (Auctores.) — *A genus of the falcon family thus 

 characterised. Bill short. Nostrils somewhat oval. Shanks elon- 

 gated and smooth. Shins plated with scales, the sutures scarcely 

 perceptible. — Vigors.* 



ACCIPITRES (Linnjeus.) — 'Birds of prey, the first of the Linnaean 

 orders, corresponding with the Rapaces of Temminck, and the JRaptores 

 of Illiger.* 



AFRICAN HERON.— A name for the Purple Heron. 



AILSA COCK. — A provincial name of the Puffin. 



AIR CELLS OF BIRDS.— * The lungs of birds have several open- 

 ings, communicating with corresponding air-bags or cells, which fill the 

 whole cavity of the body from the neck downwards, and into which the 

 air passes and repasses, in the process of breathing. This is not all : 

 the very bones of birds are hollowed out with the design of receiving 

 air from the lungs, from which air pipes are conveyed to the most solid 

 parts of the body, and even into the quills and plumelets of the feathers, 

 which are hollow or spongy for its reception. As all these hollow 

 parts, as well as the cells, are only open on the side communicating with 

 the lungs : the bird requires only to take in a full breath to fill and 

 distend its whole body with air, which, in consequence of the consider- 

 able heat of its body, is rendered much lighter than the air of the 

 atmosphere. By forcing this air out of the body again, the weight 

 becomes so much increased, that birds of large size can dart down 

 from great heights in the air with astonishing velocity. The struc- 

 ture of insects is not a little analogous. 1 



ALAUD A (Linn^us.) — * The Lark, a genus thus characterised. Bill 

 somewhat conical, short, with the mandibles of equal length, the upper 

 slightly convex ; nostrils at the lateral base of the bill, oval and partly 

 concealed by small reflected feathers. Feet with three toes before and 

 one behind, the anterior ones entirely divided, and the claw of the hind 

 toe very long and nearly straight. Wings with the first quill very 

 short or wanting, and the third longest ; greater coverts, in most 

 instances, shorter than the quills ; feathers on the crown generally 

 long and capable of being raised like a crest. 



The British species are the Sky-Lark and the Wood-Lark ; the Pipet- 

 Lark (Anthus) is now separated from the genus.* 



ALCA (Linnaeus.) — *The Auk, a genus thus characterised. Bill 



See Insect Transformations. Page 334. 



