No.377-] THE ORIGIN OF THE MAMMALIA. 323 
the heads of the ribs are intercentral or articulate between the 
centra and the tubercles to the succeeding vertebrze (as in 
mammals). Certain structures in the dorsal (D.—12) vertebrz 
resemble a zygophen-zygantrum articulation, compensating per- 
haps for the impérfectly developed zygapophyses. In the poste- 
Descereling 
transverse 
palatine 
Fic. 9. — shen“ of Cynognathus platyceps, showing the nese ances apes of the lower jaw, 
ti a large basioccipital 
the descending 
beng "a natural size. Als Seeley. ) 
rior dorsals the ribs are suturally anchylosed to the vertebre 
and extend outwards into overlapping plates. Only two of the 
supposed sacrals are anchylosed. 
The pelvis is remarkably mammalian in the structure of its 
ventrally united ischium and pubis, with obturator foramen (rudi- 
mentary in Dicynodon), the three bones forming the acetabulum. 
But it differs from the early mammalian type in the widely 
