576 



TEXTBOOK OF ZOOLOGY 



is composed of a pair of triradiate bones, or innominate bones. Each 

 innominate bone consists of three separate bones : the ilium, ischium, 

 and pudis. These three bones radiate from a triradiate suture at 

 the acetabulum or hip socket. The pelvic girdle articulates with the 

 sacral vertebrae by means of the ilia. The ischia are the most pos- 

 terior bones of the three. The pubic bones extend anteroventrally 

 and unite at the pubic symphysis. As in the forelimb, the structure 

 of the hindlimb is of the characteristic vertebrate type. 



Cfav//'c/e__ 

 Bpkorocoid.^. 



Coracoid fenestra 



Epbternum 



Sternum 



Posterior 

 cornu 



■n Supra scapula 



Scapula 

 -Pre coracoid 

 -Coracoid 

 —Humerus 



-Vontanelle 



- -Trochlea 

 -.Olecranon 

 --Radius 



Ulna 



Styloid P. 



--Carpals 

 Metacarpal 

 PholarK^es 



Fig. 302. — Sternum, pectoral girdle, and disarticulated forelimb of horned lizard, 



ventral view. 



Muscular System 



The reptilian musculature shows few unusual characteristics. In 

 a general way it may be said to be intermediate between that of 

 amphibians, on the one hand, and birds and mammals, on the other. 



Since the horned lizard is a generalized terrestrial animal, the 



musculature follows the typical vertebrate plan rather closely. 



/ 



