TORTOISES 



247 



Family i: Pond, Marsh, and River Tortoises (Emydae). 



The European Pond or Marsh Tortoise (Emys europ(ea). 

 (Total length up to 12 inches.) 



A. Body Armour. 



The body is toadlike, and enclosed in a shield or body armour con- 

 sisting of two portions, covering respectively the back and abdomen, and 

 known as the carapace and the plastron. 



W., vertebral column. 

 Sch., bones of the shoul- 

 der girdle. 

 0., humerus. 

 E., ulna. 

 Sp., radius. 

 Hw., carpal bones. 

 Mh., metacarpal bones. 

 B., pelvis. 

 Osch., femur. 

 Schb., tibia. 

 Wb., fibula. 

 Fw., tarsal bones. 

 Mf., metatarsals. 

 Wp., neural plates. 

 R., ribs. 



Rp., costal plates. 

 Rdp. , marginal plate. 

 Np., nuchal plate. 

 Schp., pygal plates. 



SKELETON AND BODY ARMOUR OF POND TORTOISE. 



I., Skeleton and dorsal shield (carapace) from below. 



II., ventral shield (plastron), composed of dermal bones from above (internally). 



III., plastron from below (outwardly). 



IV., carapace from above (outwardly). 



III. and IV. with the horny epidermic plates covering the bony plates. 



1. When viewed from their inner side, both shields are found to 

 consist of bony plates, which are rigidly united with each other by serrated 

 sutures (see Part I., p. 11, Section a). 



The small plates which form the central row of the dorsal carapace 

 .are intimately anchylosed with the vertebral column, being, in fact, 



