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MANUAL OF ELEMENTARY ZOOLOGY 



unites with its fellow in a symphysis. The ischium and 

 pubis are separated by a large obturator foramen, above and 

 below which they meet. Above the obturator foramen all 

 three parts of the os innominatum are continuous around 

 the acetabulum, into which the head of the femur fits. 



The limbs contain the same bones as in the frog. In 

 the fore-limb the humerus has in front of the head a 



bicipital groove for the 

 tendon of the biceps 

 muscle, bounded by two 

 roughened projections, 

 on the inner side the 

 lesser tuberosity or small 

 tubercle, and on the 

 outer side the greater 

 tuberosity or large 

 tubercle. At the lower 

 end is a pulley -like 

 trochlea, above which 

 are two supratrochlear 

 fossa, the coronoid fossa 

 in front and the ole- 

 cranon fossa behind, a 

 supratrochlear foramen 

 putting the two into 

 communication. In the 

 forearm the radius and 

 ulna are distinct but 

 not movable upon one 

 another, the radius lying 

 in front of the ulna. 

 In man the lower end 

 of the radius rotates round the ulna, so that the former 

 lies in front of and obliquely across the latter when the 

 palm faces downwards, but parallel with and outside it 

 when the palm is turned upwards. The position in which 

 the palm is downwards is known as pronation, that in 

 which it is upwards as supination. In the frog the limb 

 is fixed half-way towards pronation ; in the rabbit it is 

 fixed in the prone position. A large olecranon process of the 

 ulna fits into the olecranon fossa. In the wrist all the 



Fig. 318. — The pelvic girdle of a 

 rabbit, from beneath. 



ac. , Acetabulum; il. , ilium; 

 ob.f., obturator foramen ; $u- 

 symphysis pubis. 



is., ischium ; 

 pubis ; sym.. 



