56 THE SKELETON OF THE FROG. 
iii, The coracoid: a stout bone, wider at its inner 
than its outer end: it connects the posterior 
edge of the scapula with the sternum. 
c. The sternum: lies in the mid-ventral line: it consists 
originally of two lateral halves which fuse completely 
in front and behind, but remain distinct in the 
median portion. It presents from before backwards 
the following parts :— 
i, The episternum: a flat circular plate of cartilage. 
ii. The omosternum: a slender bony rod projecting 
forwards in front of the clavicles. 
iii, The epicoracoids; a pair of narrow strips of carti- 
lage closely applied to one another, and lying 
between the ventral ends of the precoracoids and 
coracoids. 
‘iv. The sternum proper: a rod of cartilage ensheathed 
in bone projecting backwards behind the 
coracoids. 
v. The xiphisternum: a broad expanded plate of 
cartilage. 
2. The fore-limb. 
The bones, which are all cartilage bones, are elongated with 
enlarged ends, excepting the small bones of the wrist. The 
enlarged ends or epiphyses ossify independently of the shaft of 
the bone, with which they do not unite until late in life: the 
extremities are capped with articular cartilage. The end of a 
bone which, when the limb is extended, is nearer to the body 
is called its proximal end, the opposite extremity the distal end. 
a. The arm: in the arm there is only a single bone. 
i. The humerus: the proximal end or head is 
enlarged, and articulates with the glenoid cavity 
of the pectoral girdle: below the head is the 
strong deltoid ridge extending along the proximal 
half of the anterior surface. At the distal end 
is a Spheroidal articular surface for the bone of 
the fore-arm: and at either side of this a 
