Professor Marsh’s Monograph of the Dinocerata. 179 
“The orbit is large, and confluent with the temporal fossa. 
The latter is of great extent posteriorly, but the zygomatic 
arches are only moderately expanded. There is no post-orbital 
roc 
eS. 
“The nasal bones are greatly elongated, being nearly half 
the length of the entire skull. They project forward over the 
ceras and Tinoceras, is formed of an osseous projection, 
cong forward and downward, and situated in front of an 
low the nasal protuberances. Several specimens in the Yale 
useum show that this projection is formed of two separate 
ossifications, each in front of ‘its respective nasal bone. 
2. 
Mievre 2—Siull of Dinoceras mirabile, Marsh; seen from the left. One-sixth 
“ 
natural size. : 
These bones are a peculiar feature in the skull of Dino- 
rata, and may he elle” the pre-nasal bones. In very oe 
cae they are unossified; in adult animals, they are 
» as in he § i en E 
become eodesified ‘with the aasals, and with cach oth 
