ORDER CHELONIA. 543 



The carapaceis highly arched and very strong in the Land-Tor- 

 toises (Fig. 316); but more flattened in the aquatic families, for 

 the better adaptation of their form to motion in a liquid. The 

 plastron differs considerably in degree of development, and in the 

 relative consolidation of its different parts. It is most complete 

 in the Land-Tortoises ; in many of which, the anterior and 

 posterior portions of it are so jointed to the centre-piece, as to 

 be able to close the orifices before and behind, after the head, 

 tail, and legs have been drawn in, thus affording to the animal 

 a most excellent means of passive defence. The natural food 

 of many of the Chelonia is vegetable, and they can endure long 

 fasting with impunity ; there are some species, however, which 

 are carnivorous, and which show much ferocity of disposition. 

 They are extremely tenacious of life ; surviving the severest 

 mutilations for days or even weeks. Their movements are 

 usually slow and awkward ; but they continue them with great 

 perseverance, and for a long time, apparently without fatigue, so 

 as to produce effects which would not have been anticipated. 

 Their sensations appear to be very obtuse ; and altogether they 

 may be said to live very slowly. Connected with this slowness 

 appears to be the remarkable length of their lives ; which has 

 been known to exceed (in the case of a Garden Tortoise) two 

 hundred and twenty years, and may have been much more. 

 The Chelonia are divided, according to the form of their shell 

 and extremities, into five families: 1. TESTUDINID^E, or Land- 

 Tortoises ; 2. EMYDIDJE, or Marsh- Tortoises ; 3. CHELYDIIXS:, 

 or Frog -Tortoises; 4. TRIONYCIDJ:, or River- Tortoises ; and 

 o. CHELONID^E, or Turtles (Marine Tortoises). 



484. The TESTUDINID^ are slow, quiet, inoffensive animals ; 

 feeding upon vegetable substances, and seldom wandering far 

 from their usual haunts. They are for the most part inhabit- 

 ants of the warmer regions of the globe ; though many species 

 will bear removal to colder climates, passing the winter, how- 

 ever, in a torpid state. The Testudo Grceca, of which the 

 upper and under surfaces are shown in Figs. 316 and 317, is 

 the species best known in this country; it is a native of the 

 South of Europe ; but it will live in our gardens for many yours 



