LIMBS 435 



hip or pelvic girdle supporting the hind-limbs. Formed of cartilage 

 in the embryo, they consist almost entirely of cartilage bone in 

 the adult. 



The shoulder girdle (Fig. 344) practically consists of one bone, 

 the scapula, on each side. This is a flat, triangular structure, with 

 the apex directed downwards and forwards, and bears a prominent 

 external ridge or spine, which at its lower end becomes free as an 



t.3 



g.t. 



^tro. 



Fig. 346. — Bones of the rabbit. 



A, The sacrum, from above ; B, a segment of the skeleton of the thorax, from in front ; C, the left humerus 



from in front ; C, the same, from behind ; D, the left femur, from in front. 

 ^z., Prezygapophysis ; b.g., bicipital groove; cap., capitulum ; cd.t., condyles for the tibia; c.d.i, first 



caudal vertebra ; cm., centrum ; cor.f., coronoid foramen ; d., deltoid ridge ; g.t., great trochanter ; 



g.tu., greater tuberosity ; h., head ; l.t., lesser trochanter ; l.tu., lesser tuberosity ; n.a., lamina of neural' 



arch ; n.s., neural spine ; olf., olecranon fossa ; pr.l., process for the attachment of hgament ; s.t.f., 



supratrochlear foramen ; sac, sacral vertebra ; St., sternum ; st.r., sternal rib ; ^.3, third trochanter ; 



tr., transverse process ; tro., trochlea ; v.c, vertebral foramen ; v.r., vertebral rib : iv., process for the 



ilium. 



acromion with a long, backward metacromion. At the apex is the 

 shallow glenoid cavity for the humerus, in front of which a small 

 hook or coracoid process represents the coracoid, which is a 

 separate bone in the frog. Along the convex dorsal border hes 

 a narrow cartilaginous suprascapula. The clavicle is a slender, 

 curved membrane bone, lying in a ligament between the acromion 

 and the sternum. In mammals which move the forearm freely, 

 as in man (Fig. 440), it is well developed and articulates with 

 acromion and sternum. 



The hip girdle (Fig. 345) is large, and each of its halves is 



