THE SKELETON 4 
As already stated, the presence of a free rib in connection 
with the last cervical vertebra (Fig. 27, A) is somewhat rare in 
Fic. 25.—DIAGRAM OF A TRANSVERSE SECTION OF THE Hip GIRDLE AND Sacrum: A., OF 
A SALAMANDER ; B., oF MAN (young stage in which the separate parts of the sacral 
vertebre are still distinct). 
b.v., body of sacral vertebre ; a.7., arch of same; 7.s., sacral rib; 7., ilium ; 
p., pubis ; ¢.h., ceelom ; ac., acetabulum. 
adults, but the vestige of such a rib, and even of a second (some- 
what less attached) near the sixth cervical vertebra,is almost always 
ITY y 
I ea 
WA 
Fic. 26.—A, First THORACIC SKELETAL SEGMENT FOR COMPARISON WITH B, FIFTH 
CERVICAL VERTEBRA (MAN). 
¢., first sternal rib ; c’, cervical (rib which has become united with the transverse process 
(tr.)) the two enclosing the costo-transverse foramen (f.c.t.) ; 2y., articular process 
of the arch (zygapophysis) ; 6.v., body of vertebra ; s¢., sternum. 
found in the embryo. The five anterior cervical vertebrae show 
no such distinct vestiges, although their former presence is clearly 
