76 



General Biology 



is made of cartilage, a coracoid ( ), a precoracoid 



or epicoracoid, and a clavicle ( ) fused together. 



At the meeting of coracoid and scapula there is a little smooth cavity 

 where the arm joins the girdle called the glenoid fossa ( ). 



Where coracoid and clavicle meet at the mid line on the ventral side 

 of the body, there are four bones. These four actually are a part of the 

 axial skeleton, but are usually classified as a part of the appendicular 

 as well. The most anterior one of the bones is called the episternum, 

 the one between this and the clavicle is the omosternum, while the pos- 

 terior one closest to the omosternum is the mesosternum, and the one 

 projecting farthest backward is the xiphisternum. 



The fore limbs are made up of a long bone, the humerus 

 ), joining the pectoral girdle in the glenoid fossa 

 ) and with the radio-ulna at 

 ). This latter bone constitutes the 

 skeleton of the fore arm and in reality consists of two bones, the radius 

 and the ulna, fused together. 



( 



at its proximal end ( 

 the distal end ( 



B '«* 



Fig. 22. The Pelvic Girdle and Leg. 



A. Pelvic girdle complete. 



B. One side of pelvic girdle: II., ilium; Isch., ischium; Pu., cartilaginous 

 pubis; Ac, acetabulum. 



C. Femur of the frog: p., proximal; d., distal articulating surfaces; s., shaft. 



D. Tibio-fibula, seen from below: p., proximal; d., distal articulating sur- 

 faces; t., tibial half of the bone separated by a groove from /., the fibular half. 



E. The right ankle and foot of the frog, seen from below: This figure is 

 drawn to a larger scale than A and B. a., astragalus; c, calcaneum; / — V., the 

 five principal digits; X., the minute accessory digit. (From Bourne after Ecker.) 



The wrist possesses six bones, the ulnare ( ), 



radiale, ( ), intermedium, and three carpals 



( )• 



The hand has five proximal metacarpal ( ) 



bones, followed in digits ( ) II and III by two 



phalanges ( ), and in digits IV and V by three 



phalanges. 



The pollex, ( ) or thumb, is rudimentary. 



