( 3 ) 
from the middle. It is formed of five pieces : a middle, of which 
this projecting plate is a part ; two anterior lateral for the attach- 
ment of the ribs ; and two exterior lateral for the extension of its 
surface, (i) The greater or lesser degree of ossification of the 
latter denotes more or less vigour for flight. The furcula, pro- 
duced by the union of the two clavicles, and the two powerful 
supports or buttresses formed by the coracoid apophyses, (2) keep 
the shoulders widely apart; the wing sustained by the humerus, 
by the fore arm, and by the hand (which is elongated, shewing 
one finger and the vestiges of two others), (3) bears a row of 
elastic pens along its whole length, considerably extending the 
surface which strikes or gives the shock to the air. The pens 
adhering to the hand are called primary, and there are always 
ten ; those which proceed from the fore arm are called secondary, 
their number varies ; the weaker feathers attached to the humerus 
are called scapulary; the bone which represents the thumb has 
also some pens, called bastards. (4) 
(1) These five pieces are only distinct in the young bird ; see the 
sternum of a fowl, fig. 15, from Geoffroy's Memoir in the 10th volume 
of the 'A nnales de Musee^ wherein he observes, that, in general, one 
half of the sternal ribs, r r, proceed from the anterior laterals, and the 
other half from the posterior laterals ; but it sometimes happens, that 
the greater number, or even the whole, are attached to the former : 
a a are the anterior laterals^ p p the posterior 5 s is the part corres- 
ponding to our sternum. 
(2) See pi. 1. The apophysis is the base or round end of the bone, 
fitting into the opposite socket; the epiphysis is a small bone articu- 
lated on the upper surface of the extremity of a large bone, as in the 
humerus of pi. 1 : the trace of these articulations remains distinct in 
Mannnalia for six or seven years ; but in Birds they are obliterated 
very soon after birth, their more active life demanding and perfecting 
an earlier ossification of the epiphysis. We know that the bony 
matter is deposited by the blood of the arteries, whilst the calcareous is 
carried off by the lymphatic vessels ; consequently, as the circulation 
of Birds is much more rapid, from the stimulus of the greater propor- 
tion of oxygen, the bony matter is supplied and appropriated much 
more speedily than in Mannnalia. 
(3) In Mammalia it is always the middle finger which is rudimen- 
tary when the others are wanting ; hence it is concluded to be the 
middle finger which is the most perfect in the arm or wing of Birds \ 
see pi. j. 
(4) See fig. 17, the bones of the wing of a common Sparrow; 
also fig. 16. The primaries are also called the greater remiges^ 
and the secondaries the lesser; the lower scapularies are called the 
tectrices majores, the upper the tectrices minores ; the tectrices sca- 
palare-s are situated at the lateral edge of the wing nearest the body 
