412 



COLLEGE ZOOLOGY 



Figure 279. Malademys, the diamondback ter 

 rapin. It derives its common name from the mark- 

 ings on its shell. One of the most famous of all 

 turtles as food for man. (Courtesy of Shedd Aqua- 

 rium, Chicago.) 



Testudo (Fig. 274), which are found on the 

 Galapagos Islands, have been known to 

 weigh over 500 pounds and are probably 

 over 200 years old. 



Sea turtles inhabit tropical and semitrop- 

 ical seas and come to land only to lay their 

 eggs on sandy beaches. Their limbs are 

 modified as paddles for swimming. The 

 leatherback turtle Dermochelys (Fig. 274) 

 is the largest of all living turtles, sometimes 

 attaining a weight well over 1500 pounds. 

 It has a leathery covering over the shell in- 

 stead of horny shields. Soft-shelled turtles 

 (Fig. 280) also have shells that are leathery 

 and without shields. 



Sphenodon, a living fossil 



Sphenodon is the sole surviving species 

 (Fig. 283) of the order to which it belongs. 

 Numerous skeletal characteristics are like 



Figure 280. Amyda, the soft-shelled turtle. Length of shell of adult about one foot. Accord- 

 ing to Ditmars, a large specimen can amputate a man's finger. Note the leathery integument 

 which is not divided into horny scutes. (Courtesy of N.Y. Zoological Society.) 



those possessed by some of the oldest fossil 

 reptiles, and the ancestors of living reptiles 

 were apparently much like this queer relic 

 of past ages. Sphenodon is now restricted 

 to some small islands in the Bay of Plenty 



in New Zealand; and because it is now pro- 

 tected, it is thriving with an estimated 

 5000 on Stephen Island alone. It is about 

 two feet long and resembles a lizard in form. 

 It lives in burrows, is nocturnal, and feeds 



