VI INTRODUCTION. 



water along accustomed routes. When drinking the head is plunged into 

 the liquid, which is taken slowly in gulps, as if to prolong the enjoyment 

 as much as possible. South America and the Galapagos Islands possess 

 the largest living species. Our largest is the "Gopher" of the Southern 

 States, Xerobates. "Box Tortoises," Cistudo, are not uncommon east of 

 the Rocky Mountains. In these both valves of the plastron are hinged, 

 and, when the head, tail, and limbs are drawn within, can be closed tightly 

 against the carapace. 



Mud Turtles have a more elongate shell than the preceding; and the 

 height, compared with the length, is less. In structure the plastron varies 

 considerably, most often it is rigid ; one or the other, or both, of the lobes 

 may be hinged. Their food is mixed — animal and vegetable. Species 

 of Emys, Cinosternum, and Ozotheca are common examples. One of the 

 largest that might be placed in this group is the gigantic river tortoise 

 of the Amazons, Podocnemys. The largest North American inland turtles 

 are the "Snappers," Chelydra, and Gypochelys. In them the head is large, 

 tail long, and plastron reduced in size. 



Freshwater Turtles, such as belong to the genera Amyda, Platypeltis, and 

 Aspidonectes, are seldom seen on the land. Their shells are much depressed 

 and the margins are leathery. The nostrils are produced beyond the snout 

 in a sort of proboscis, which admits of taking air without disturbing the 

 surface of the water or showing the head. They are carnivorous, and feed 

 on fishes, batrachians and worms. The feet are webbed, furnished with 

 strong claws, and the marine species are hardly more expert in swimming. 

 Some of these are quite as savage as the snappers. 



The flesh of the majority of the land, mud, and water species is excellent. 

 When brought to market they are ordinarily known by the name "Ter- 

 rapin," though that best known by this title is the marsh turtle, Malaco- 

 clemmys palustris. 



Sea Turtles are numerous off the coasts of Florida. " Trunk-backs " or 

 "Leather-backs," Sphargis, are the largest, attaining more than a thousand 

 pounds in weight. As the common name suggests, carapace and plastron 

 are not ossified as in other marine genera. Sphargis is very erratic. Speci- 

 mens from the Gulf of Mexico find their way northward to the coasts of 

 New England, and are supposed to cross the Atlantic, individuals having 

 been taken at the British Isles. Loggerheads, Thalassochelys, are more 

 common. These reach a weight of four hundred pounds. They are said 



