4 
ALCA. 
the second nearly half as long as the third, which is the longest. The 
hedge-chanter f A. modularis ) is the only British species of the genns.* 
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 (Linn^us.) — * Birds of prey, the first of the Linmean 
orders, corresponding with the Rapaces of Temminck, and the Raptor es 
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 rejiasses, 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.^ 
ALAUDA (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 v,j 
toe very long and nearly straight. Wings with the first quill very B 
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.* jp 
ALCA (LiNNiEus.) — *The Auk, a genus thus characterised. Bill f 
See Insect Transformations. Page 334. 
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