o4 THE AMERICAN MUSEUM JOURNAL 
with perfect ease and quickness by a serpentine movement of its body 
and flattened tail, its legs meanwhile being closely pressed to its side and 
motionless. his is also the method of propulsion of crocodiles when 
swimming. 
The carnivorous or flesh-eating dinosaurs that lived on land, such as. 
Allosaurus and Tyrannosaurus, were protected from foes by their sharp 
biting teeth, while the land-living herbivorous forms were provided with 
defensive horns, as in Triceratops, sharp spines as in Stegosaurus or 
were completely armored as in Ankylosaurus. 'Trachodon was not 
provided with horns, spines or plated armor, but it was sufficiently pro- 
tected from carnivorous land forms by being able to enter and remain 
TRACHODON TAIL. 
Fragment preserving an impression of the skin. 
in the water. Its skin was covered with small raised scales, pentagonal 
in form on the body and tail, where they were largest, with smaller 
reticulations over the joints but never overlapping as in snakes or fishes. 
A 'Trachodon skeleton was recently found with an impression of the 
skin surrounding the vertebrae which is so well preserved that it gives 
even the contour of the tail, as is shown in the illustration on this page. 
During the existence of the Trachodonts, the ciimate of the northern 
part of North America was much warmer than it is at present, the plant 
remains indicating a climate for Wyoming and Montana similar to what 
now prevails in southern California. Palm leaves resembling the pa!- 
