Prof. O. C. Marsh—Neu Jurassic Dinosaur. oor 
base of the skull were undisturbed, a careful search was made for 
the stapes, but no indication of it was found. Its absence in this 
specimen, so well preserved, would indicate that it was wanting in 
this genus, if not in the other Sauropoda. 
Columella present.—In a skull of Brontosaurus in which the bones, 
although displaced, were in very perfect preservation, a pair of 
bones were found which apparently are the columelle. They are 
elongated, flattened bones, with the shaft somewhat constricted in 
the middle, and twisted. Their length corresponds to the elevated 
posterior part of the skull in this genus. 2 
Hyoid bones.—There are two pairs of hyoid bones in the Sauro- 
poda. They are elongated, rodlike, and somewhat curved. In Bronto- 
saurus excelsus, they are 210 and 180 mm. in length respectively. 
Among the other points of interest in the skull of the Sauropoda 
are the following :—The parietal bones are very short, and form but 
a small portion of the brain case. They are composed chiefly of the 
flattened arched processes, which meet with the squamosals at their 
outer ends. There is no parietal foramen. The squamosals lie upon 
the par-occipital processes. They have a short deep groove for the 
reception of the post-frontal. On their lower part, which descends 
in front of the par-occipital process, they expand into a thin spoon- 
shaped form, which fits over the head of the quadrate. The quadrate 
has an oval rounded head, and slender shaft. Below, it is firmly 
united to the pterygoids. On the outer side, the quadrato-jugals are 
attached. These bones are elongate, and slightly sigmoid in shape. 
The lower end is rodlike, and curved forward, descending below the 
articular surface of the quadrate. The pterygoids are tri-radiate 
bones, with the posterior ends cup-shaped, resembling the partially 
closed human hand. This cavity, somewhat restricted by a thumb- 
like process, receives the basi-pterygoid process. 
The Vertebre.—_There are twenty-seven precaudal vertebra in 
Brontosaurus, of which the first twelve bear pleurapophyses, or 
hatchet bones, united to the centra, and may hence be called true 
cervicals. Of the remaining twelve which bear free ribs, the. 
thirteenth, fourteenth, and fifteenth have the surface for the articula- 
tion of the head of the rib on the centrum, below the neural suture. 
All the precaudal vertebree have large cavities in the centrum, 
communicating exteriorly with the surface by means of large lateral 
foramina. This cavernous structure of the vertebre graduaily 
decreases posteriorly, until in the anterior caudal vertebre it is con-, 
fined to a small pocket above the transverse process. The neural 
arches of the presacral vertebra: contain numerous deep cavities. 
The pleurapophyses of the cervical vertebree are also reticulate im: 
their structure, and some of the anterior ribs have small but deep 
fossee below the tubercle. 
Post-metapophyses.—On the last two or three cervical vertebre of 
Brontosaurus, there is a convoluted ridge of bone over the posterior 
zygapophyses. In the anterior dorsals, this ridge becomes stronger 
and more elongated, forming a distinct protuberance. These pro- 
cesses have not hitherto been described. As they are analogous to 
