THE SKELETON OF NAOSAURUS 39 
of the spines of the vertebre greatly elongated, and each spine bears a 
series of little cross bars, the arrangement suggesting the masts and 
yards of a square-rigged ship, whence the name of Nao-saurus or “‘Ship- 
Lizard.” ‘This remarkable specimen is a part of the Cope Collection 
of Fossil Reptiles which was presented to the Museum by President 
Jesup a few years ago. ‘The bones were collected in the Permian beds 
of the Wichita river region, Texas, by Charles H. Sternberg. 
The spines of Naosaurus spread out like the sticks of a fan and 
during life were probably connected by tough, horny skin, though not 
covered with flesh, for without scme such connecting tissue the spines 
might easily be wrenched out of place, dislocating the backbone, since 
the fin is an extension of the vertebrae, unlike the fins of fishes, which 
are independent of the backbone, or the crest of the Iguana, which is 
simply an outgrowth from the skin. Although the large sharp teeth 
are well adapted to seizing and tearing the animal’s prey, they are 
curiously ill-fitting, and apparently the jaws could not be tightly closed. 
The under side of the body was covered with bony scales. 
The use of the great back fin has not yet been satisfactorily explained. 
It may have served partly to protect the backbone, always the most 
vulnerable part in such animals, but more probably it was chiefly orna- 
mental. Suggestions that it served to conceal the animal by resembling, 
to the untutored eye of its prey, the reeds and rushes among which it 
lurked, or as a sail to enable it to traverse the waters of the Permian 
rivers and lakes, need not be taken very seriously. 
Although clumsy and awkward looking in comparison with the 
more highly developed carnivorous reptiles and mammals of later 
periods, the Naosaurus was the most active and powerful predaceous 
animal of its time. <A suggestion of its fighting habits is conveyed in the 
injury to one of the spines in this skeleton. ‘This was broken and dis- 
placed during life, probably in some affray, and afterwards united by a 
growth of false bone. Several other specimens in the collection bear 
marks of injuries received during life. 
With this skeleton the Department of Fossil Vertebrates enters upon 
the illustration of the fauna of the Age of Amphibians, which preceded 
the Age of Reptiles as that preceded the Age of Mammals in the history 
of the earth. In the Hall of Fossil Mammals may be seen the rise and 
development of the various races of quadrupeds which to-day inhabit 
the earth; while the Dinosaurs, in the Dinosaur Hall, and the Marine 
