796 



PHYLUM CHORDATA : CLASS MAMMALIA 



In front of the knee there is a sesamoid bone — the knee-pan or 

 patella — and posteriorly there are smaller fabellae. 



Fig. 477. — Pelvic girdle and terminal vertebrae of a gibbon. — 



From a Specimen. 



IL., Ilium ; S.F., the first of the two true sacral vertebrae ; C, the second last caudal 

 vertebra ; AC, acetabulum, formed from the junction of ilium, ischium {IS.), 

 and pubis (P.) ; P.S., pubic symphysis extending far back to meet the ischium; 

 the ischium and pubis enclose the obturator foramen. 



In the lower leg, the tibia, which corresponds to the radius, is pre- 

 axial, and in the normal position interior ; the fibula, which corresponds 



