514 0. C. Marsh—American Jurassic Dinosaurs. 
The largest species of this genus at present known may be 
called Morosaurus robustus. It can readily be distinguished 
from those already described by its short, helmet-shaped, ilium, 
which is represented in Plate VIII, figures 1 and 2. 
One species of this genus, Morosaurus grandis,* is now known 
by a nearly complete skeleton, and the remains here figured are 
mainly portions of this individual. They were found together 
in nearly as perfect preservation as in life, and many of them 
were in their natural position. The locality was in peg 
and the bones were taken out with great care by Mr. 8. W. 
Williston of the Yale Museum. 
This animal when alive was about forty feet in length. It 
walked on all four feet, and in many other respects was very 
unlike the typical Dinosaur. It must have been very sluggish 
in all its movements. Its brain was proportionately smaller 
than in any known vertebrate. 
Diplodocus longus, gen. et sp. nov. 
removal, measured from the head of the femur to the end of 
the toes over thirteen feet (4:1™). The femur was 16450™ In 
length, and the tibia 1090™™, Four of the median caudal ver- 
tebrae measured together thirty-four inches (760™). The first 
of these, or the fourteenth in the series, was eight and one-half 
inches (217™) long, and five and one-half inches (140) across 
the anterior end. 
The peculiar chevron represented in Plate VILL, figure 3, was 
found attached to the eleventh caudal, and all the remaining 
chevrons observed were of this character. Figure 4 represen 
a specimen found at another locality, and perhaps belonging to 
a different genus. 
The above remains indicate a reptile about fifty feet in length. 
They were found in the upper Jurassic, near Cafion City, Col- 
orado, in 1877, by Mr. 8S. W. Williston. 
* This species, when described by the writer, was referred provisionally to the 
genus Apaiosaurus. This Journal, vol. xiv, p. 515. 
