D rayons of Sea ami . 1 // 



Ornithostoma was at once the largest and 

 lightest of flying creatures, exceeding in this 

 respect even the frigate-bird, although that 

 might almost be termed an appendage to a pair 

 of wings. 



These flying reptiles naturally suggest the 

 question as to whether Ornithostoma, the wild 

 swan, and the condor mark the limit of size 

 attainable by flying animals. They vary in 

 spread of wing from 20 feet in the pterodac- 

 tyl and 10 feet in the condor to 8 feet in 

 the swan. In weight they approach one an- 

 other more closely, a large condor weighing 

 about 20 pounds,* a swan 25, and a pterodac- 

 tyl (estimated) 25 to 30 pounds. The swan 

 flies by strokes of its wings, the condor soars, 

 the pterodactyl probably sailed. Are the diffi- 

 culties in the way of using wings so great that 

 evolution has stopped at a weight of 30 pounds 

 and a spread of 20 feet ? The reader may an- 

 swer this question to suit himself or herself; 



* No dependence can be placed in most statements regarding 

 the size and weight of birds and other animals. For the most 

 part they are no better than guesses, and very wide of the mark, 

 as the application of rule and scales will quickly show. 



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