AVES. 
155 
composed originally of five pieces : one medial (fig. 68, a), of which this salient lamina 
[known as the sternal crest, ridge, or keel] constitutes a part ; two triangular anterior la- 
teral [termed costal processes] (6), for the attachment of the ribs ; 
and two forked posterior lateral (c), for the extension of its sur- 
face ; and the greater or less degree of the ossification [that is to 
say, obliteration] of the notches of these last, and the extent of 
the interval which is left between them and their principal bone, 
denote the relative amount of vigour of flight in Birds. The 
[Eagles, Harriers, (the Falcons much more slowly, if indeed at 
all), and some other] diurnal Birds of prey, the Swifts and the 
Humming-birds, [the Parrots, and also the Storm-petrels,] lose, 
as they grow old, all traces of these unossified spaces. [In the 
Ostrich and its allies, the sternum is composed originally of only two pieces ; and the 
number likewise varies in those Birds which possess a sternal crest.] 
The fourchette \_furcula, or “ merry-thought” bone], (fig. 68, d), produced by the 
junction of the two clavicles, and the two stout abutments formed by the [huge] 
coracoid aphophyses (e), keep the shoulders apart, notwithstanding the opposing force 
exerted by the action of flying ; the fourchette, in particular, is commonly more stout 
and open, according as the flight of a Bird is vigorous.* (See fig. 67.) The 
wing, supported by the humerus (fig. 69 «,) fore-arm 
Fij?. 68.— Sternal apparatus of a 
newly-hatched Chick. 
(i), and hand, which is elongated, and exhibits one 
digit and the rudiments of two [or (including the 
winglet 0 ,) three] others (1,2,4) is furnished through- 
out its length with a range of elastic quills, which greatly 
extend the surface that resists the air. The quills ad- 
hering to the hand are named primaries, and these are 
[almost] always ten in number f ; those attached to 
the fore- arm are called secondaries, but their number 
varies ; weaker feathers attached to the humerus are 
styled scapularies [tertiaries ; the true scapularies 
constituting that separate range which grows over 
the scapulars, or “ shoulder-blades”] ; and the bone 
which represents the thumb | (o), is also furnished 
with what are designated bastard quills, [this member 
being generally termed alula spuria, or winglet ] . Along 
the base of the quills is a range [and successive 
ranges] of feathers named coverts [both on the outer 
and inner surfaces of the wing, which receive corre- 
sponding appellations to those of the quill-feathers they 
impend, as primary coverts, &c., and are further distinguished 
I 
Fig. 69. — Jer Falcon’s Wing. 
-s greater, lesser, and least ] . 
* In the instance of the Parrots, some of which are birds of very 
strong flight, although the coracoids are always very stout (much 
resembling those of the Hawks), the furcula is never strong, and is 
peculiarly flattened, so that its resisting force is thus considerably 
diminished. Some Parroquets, indeed, as those small ones popularly 
termed Love-birds {Agrapornis) , have no urcula whatever; and it 
is worthy of being noticed that the restricted Toucans (Rhamphastos) 
have the clavicles separate and very short, forming small dagger- 
shaped appendaures, the use of which is not obvious. — E d. 
+ In the Grebe genus, eleven : many of the singing birds have the 
first extremely minute ; and, in the Starling and some others, it is, 
analogically speaking, wanting ; so that the number is in these 
reduced to nine. — E d. 
t As on the removal of digits, that of the thumb is found to be 
invariably the first, the rudimentary finger above referred to is now 
considered as analogous to the index finger of the human hand : the 
thumb, however, being sometimes represented by a bony spine ; 
as the spur of a common fowl represents the first digit of the 
foot. — E d. 
I 
