606 MUSCULAR SVSTEM 
Mammalian equivalent is the m. supraspinatus. In Ratitx it arises 
almost wholly from the coracoid, and scarcely from the sternum: 
in Carinatx the lateral margin of its sternal origin is marked by a 
ridge beginning near the coracoid and running parallel to the keel, 
or converging towards or diverging posteriorly from the latter. 
The direction and extent of this ridge afford some taxonomic help, 
as shewn thus :— 
= 
STERNAL RIDGE. 
ORIGIN OF 
MUuscLE. + 
Converging. Parallel. Diverging. 
From the whole |Spheniscide, Tinami-|Anseres (pt.), Grues, | Cypseli, Tro- 
length of the} de,Galline, Limicole | Columb, Opistho-| chili, Capri- 
keel. (pt.) comus, Psittaci. mulgide. 
From half to} Limicole (pé.), Lari, 
two-thirds. Anseres (pé.), Pheeni- 
copterus, Pelargi, 
Herodii, Stegano- 
podes, Cathartide, 
Neophron,  Striges, 
Steatornis. 
From the an-|Acciptres (plurimi\, | Passeres ( pt.) Picarie (plur- 
terior third. Colymbida, Tub'- ime), Pici, 
nares. Passeres (plur- 
imi). 
M. propatagialis longus, always present, composed of slips from 
the mm. deltoides, pectoralis, biceps and cucullaris. Its strong belly 
originates near the shoulder-joint from the clavicle, scapula and 
coracoid. Its tendon runs directly to the carpus, forming the 
outer margin of the patagium or fold of skin between the anterior 
surfaces of the upper and forearm, which it with the m. propatag. 
brevis serves to extend, and consists of yellow elastic and blue 
non-elastic fibres, the latter radiating into and being attached to 
various portions of the patagium. When the wing is extended 
the elastic portion is stretched to about three times its ordinary 
length, to which it returns when the wing is folded. 
M. propatagialis brevis, composed like the last, absent only in 
Apteryx, Casuarius, Dromxus and the Spheniscide. In other Birds 
it is often very complicated—the simplest condition being in the 
Pici, where it consists of a belly and a strong tendon, running 
down the anterior and outer side of the upper arm, and attached 
to the proximal tendon of the m. eatensor metacarpi radialis longus, 
a little below the outer condyle of the humerus. In Cuculus its 
tendon is attached simply to the ulnar fascia, below the elbow- 
joint. In most other Birds the tendon is split into several portions, 
and is further complicated by receiving slips from, and by connexion 
