13(5 



THE PELYIC ARCH. 



man and other mammals ; which attain their culminating 

 point in the reptilian type of structure, where they exist under 

 the form of true abdominal ribs. 



[ 262. The extremities are united to the trunk by two 



girdles of bone, composed in the upper of the scapular, and 



Fig. 125. Fig. 126. 



Female. Male. 



in the lower of the pelvic arches. The scapular arch presents 

 many modifications, to adapt the anterior members as instru- 

 ments for prehension and locomotion. The pelvic arch is of a 

 more uniform structure, as the posterior extremities form in- 

 struments of locomotion alone. 



263. The PELYIC AECH (fig. 125) is composed of three pair 

 of bones, which are separate in infancy, but soldered together 

 in the adult. One of these bones, the ilium (a), is firmly 



Fisr. 127. Fiff. 128. 



