TESTUDINIDJE ; EMiT>ID,E. f>45 



gured four feet four inches along the curve of the back, and four 

 feet nine inches in breadth, and weighed two hundred and eighty- 

 five pounds. It was originally brought to the Mauritius from 

 the Seychelles Islands in 1766. The EMYDID.E, or Marsh Tor- 

 toises, form an extensive family, diffused through the warmer 

 latitudes of both the Old and the New World. They have a 

 more flattened shell, of which however the carapace is completely 

 ossified; the head and neck can usually be entirely retracted 

 within the shell ; and their feet are expanded and webbed be- 

 tween the toes, four or five of which on each foot are armed with 

 sharp claws. These animals tenant swamps, lakes, ponds, and 

 small rivers ; and swim with considerable facility. On land they 

 are more active and alert than the species of the previous family ; 

 but they never venture far from the water, and invariably seek 

 it as a refuge from danger. The plastron is generally less de- 

 veloped than in the Testudinidae, and is frequently united to the 

 carapace by cartilage only: in some species, as the Chelydra 

 serpentina, the carapace and plastron are so small, that the head 

 and limbs cannot be drawn within the shell. In the Box Tor- 

 toises, on the contrary, the plastron is divided by a transverse 

 suture into two parts, which are movably attached to the cara- 

 pace ; so that the creature can not only withdraw its head and 

 limbs beneath the roof formed by the dorsal shell, but can also 

 close its habitation completely, as if by a front and back door. 

 The Emydidre are carnivorous in their habits ; pursuing fishes, 

 newts, frogs, and insects with eagerness. Some of them are 

 formidable from their size and ferocity ; this is the case with the 

 species above named, which is commonly known under the name 

 of the Alligator Tortoise. It is a native of the lakes, rivers, 

 and morasses of Carolina; and is remarkable for its activity, 

 and for the strength of its jaws, darting suddenly upon aquatic 

 Birds, Fishes, or other animals that come within its reach, and 

 snapping them up between its mandibles. It cannot be safely 

 approached even by Man. The CHELYDIDJE, in their general 

 form and the structure of the feet, agree with the Marsh-Tor- 

 toises, but the carapace is imperfectly ossified, and the head and 

 limbs are not completely retractile. The mouth also is sur- 



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