72 



TORTOISES AND TURTLES. 



Thick-Necked Nearly allied to the preceding is the thick -necked terrapin 



Terrapin. (Bellia crassicollis), from Tenasserim, Siam, the Malay Peninsula, and 

 Sumatra, which, with a second species from Borneo, constitutes a genus dis- 

 tinguished by the greater development of the bony buttresses connecting the upper 

 with the lower shell, and by the hinder part of the head being covered with small 

 horny shields. The feet are fully webbed, and the anterior vertebral shields of the 

 carapace are more or less distinctly balloon-shaped. The typical species measures 

 rather more than 6h inches in length ; and is of a general dark brown or black 

 colour, usually with some yellow markings on the plastron, and some large spots 

 of the same colour on the head. Several representatives of this genus are met 

 with in a fossil state in the Pliocene deposits of North- Western India. 



Hamilton's The handsomely coloured Hamilton's terrapin (Bamonia hamil- 



Terrapin. toni), from India, conspicuous for its black and yellow, highly 



vaulted, and three-keeled carapace, is the best known representative of a third 



genus, distinguished from the foregoing by the 

 hinder aperture of the nostrils opening behind 

 the line of the eyes, and the great breadth of 

 the palate. Like the two preceding genera, the 

 entoplastral bone of the plastron is traversed by 

 the groove formed by the union between the 

 humeral and the pectoral shields ; and the hinder 

 part of the head is covered with small shields. 

 Hamilton's terrapin has the elevated carapace 

 marked with three interrupted longitudinal keels, 

 or rows of nodose prominences ; the colour of the 

 shell being dark brown or blackish, upon which 

 are spots and streaks of yellow, and the soft parts 

 having likewise a similar coloration. While in 

 young individuals the hinder border of the 

 carapace is strongly serrated, in the adult it 

 becomes nearly smooth. This species attains a 

 length of nearly 9 inches at the present day, but 

 fossil examples found in the Pliocene rocks of Northern India were still larger. 

 These fossil specimens lived with numbers of mammals belonging entirely to 

 extinct species. There are four other species of the genus, ranging over Malayana, 

 Southern China, and Japan. 



Salt-Water The last representative of the group with a smooth palate and 



Terrapin. carnivorous habits is the North American genus Malacoclemmys, 

 distinguished from the last by the head being covered with continuous skin, and 

 by the groove formed on the plastron by the junction between the humeral and 

 pectoral shields being situated in advance of the entoplastral bone. While two of 

 the species inhabit the valley of the Mississippi, the salt-water terrapin (21. 

 terrapin) is a frequenter of the salt-marshes of the Atlantic Coast. The latter 

 has an oval and much depressed carapace, which attains a length of nearly 7 

 inches, and is characterised by the great width of the first and second vertebral 

 shields ; its general colour being either olive, witli black concentric lines, or 



upper surface of carapace of 

 Hamilton's terrapin. 



