56 THE STRUCTURE OF MAN 
between the parietals, assuming a markedly angular form (2p. — 
Fig. 38, A). Although this bone persists differently in different 
races, it is formed in the embryo from two distinct ossific centres, 
A B 
4.D. 
D t.p.p- 
7. 
Fic. 38.—A to C, Various ForMS OF THE OS INCAE (interparietal bone), 
D, E, DIAGRAM OF THE BONES OF THE OCCIPITAL REGION IN THE EMBRYO. 
(Partly after Ficalbi. ) 
1.p., interparietal ; ¢.p.p., preinterparietal ; e.0., exoccipital; s.o., supra-occipital ; 6.0., 
basioccipital ; f.m., foramen magnum. 
which, at a later stage, normally unite to form one mass with the 
supra-occipital. This fact testifies to its paired nature, and, as 
in the new-born child it is still separated by a cleft on each 
