194 Professor Marsh’s Monograph of the Dinocerata. 
“The author has since continued this line of investi 
and has ascertained that the same general law of brain growt 
is true for Birds and Reptiles, from the Jurassic to the present 
ime.” 
The small size of the brain in oral Tertiary mammals will 
be indicated by an examination of the Dinocerata skulls, with 
the brain in position, shown in figures 22, 23. This is further 
shown by figures 24-28, which represent the skull and’ brain- 
cast of various Tertiary Mammals. 
29. 
Figure 29,— Axis of Dinoceras cttviga rots front view. 
Figure 30.—The same vertebra; side v 
FIGURE 31.—Ce Prion vertebra of Tinocer aa hanes Marsh; front v 
FigoRE 32.—The same vertebra; side vie All the figures are one-fourth er 
size. «a, face for heard /. lateral foramen; nc, 0 
> odontoid process; s, neural spine; z, anterior ne ae 
’, posterior zygapophysis 
THe VERTEBR&. 
“The cervical vertebree of the Dinocerata, in their main 
characters, resemble those of the Proboscidians. The atlas 
and axis are somewhat similar to those of the elephant. The 
