FIELD BOOK OF PONDS AND STREAMS 



Habits, habitat. — This turtle lives in shallow, muddy- 

 bottomed water, never leaving it except to lay its eggs. It is 

 a scavenger as well as a voracious feeder upon aquatic animals, 

 even good-sized mussels. It thrives in an aquarium, but 

 lies much of the time half buried in the sand. Although 

 this turtle has lungs and no gills, it can stay under water a 

 long time, securing oxygen from the water which it takes 

 into its mouth. Its mouth and throat have a thin lining 

 richly supplied with fine blood-vessels, and an exchange of 

 gases, oxygen and carbon dioxide, takes place just as it does 

 in the gills of fishes. 



Breeding habits. — Clumsy and awkward as these turtles 

 are on land, they persevere in crawling out of the water to 

 lay several white, round eggs in the moist sand of the shore. 



Size. — Length about 14 inches. 



Range. — Along the Mississippi River and its tributaries 

 eastward into Pennsylvania and New York, northward to 

 Lake Champlain. 



Fig. 314. — Northern water snake, Natrix sipe- 

 don, subspecies sipedon. 



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