310 POPULAR HlSTOllY OF THE AQUAUITM. 



up to their victim, stretching their necks till the head is 

 near enough, and then suddenly snapping it with the jaws. 

 Sometimes they will pursue a frog or a fish with great 

 rapidity, and immediately tear it to pieces and devour bit 

 by bit in a very short time. They can be kept easily in 

 ponds or tanks, or any vessels turned for the purpose into 

 Aquaria, by being fed with bits of meat when living ani- 

 mals cannot be easily procured. 



The peculiar concentric furrows and markings on the 

 plates of the shell of Emys concentrica would, if constant 

 in all ages and conditions, distinguish this from all other 

 species, but in some varieties this character is scarcely 

 visible, nor does it make its appearance in the very young 

 specimens. On first leaving the egg the plates of the 

 young shell exhibit neither furrows nor markings; when 

 half-grown, the concentric furrows appear, and soon become 

 deep and strong; then, as the animal advances in age, the 

 furrows become less and less strons^lv marked, while the 

 concentric bands of colour become more and more distinct. 



The flesh of some American Fresh- water Tortoises is 

 known to constitute an article of food so delicious that it 

 does seem a pity not to make some decisive effort to 

 naturaHze them in our own country and introduce them 



