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POPULAR SCIENCE MONTHLY 



animal such an advantage that it is practically free from all its enemies 

 and in this dominant or protected condition it may become over- 

 nourished and the originally useful structures may t continue to grow by 

 a kind of inertia or momentum until they become greatly exaggerated 

 masses of flesh or inordinately developed spines, horns, feathers, etc. 

 Such a development seems to have occurred once and again in the 

 history of the world, and the most bizarre types of life owe something 

 of their condition, at least, to tins principle. The late Professor 

 Beecher, of Yale, has shown that there is a decided tendency, both in 

 plants and in animals, for a species that is nearing the point of its 

 extinction to develop a spiny or horny habit, covering itself with all 

 sorts of excrescences, seemingly in an unregulated effort to find some 

 condition which will prolong its existence. It is certain that these 

 reptiles, dominant as they were, were rapidly completing their allotted 

 span and as the end approached the spines grew ever heavier and 

 heavier, until it seems plausible to suggest that they became at last 

 a great drain on the animal's powers of nutrition and hastened in no 

 slight degree the end. 



Fig. 9. Palatal View of the Skull of Naosaurus, showing the peculiar dentition. 



