88 O. C. Marsh—American Jurassic Dinosaurs. 
called Apatosaurus laticollis. The size of the entire animal may 
be judged from this vertebra, which measures over three and a 
half feet (1:07 M) in width. This would imply a neck at this 
point not less than five or six feet wide,—a marked contrast 
to the long and slender neck of Morosaurus grandis, a verte- 
bra of which is figured in the same plate for comparison. All 
the cervical vertebre of the present species now known are 
e 
ing. With the exception of the articular faces of the centra, — 
the resemblance of these cervicals to those in some birds is — 
very striking. 
The limb bones at present referred to this species havea — 
general resemblance to those of Morosaurus, described by the — 
writer in the previous article. The pelvic bones appear to be 
more like those of Adlaniosaurus. 
The more important remains of this genus now known were © 
found in the Upper Jurassic of Colorado, by Mr. Arthur Lakes, — 
of the Yale Museum, to whom science is indebted for other — 
interesting discoveries. 
Atlantosaurus Marsh, 1877.* | 
es. 
bre are deeply excavated below on each side, leaving a com — 
salah narrow keel on the median line. From each opening — 
tween the transverse processes, a large cavity extends 1 
ward and backward into the centra, greatly lessening the weight — 
of the sacrum. These important characters were mentioned in — 
the original description, (vol. xiv, p. 87, July, 1877), in which 
the discovery of these large reptiles was first announced. 
The ilium in Atlantosaurus is comparatively short and massiv®_ 
but its exact outline has not been fully determined. Its articu- 
lations resemble those in the ilium of Morosaurus, and in t 
the ischiadic union, a post pubic projection indicated in the 
diagram by p’. The distal end is expanded, and rugose for 
union with its fellow on the median line, as shown in the pel¥ 
* This Journal, vol. xiv, p. 514, Also p. 87. 
