TRIONYCIDyE. 43 



Platysternum megacephalum. 



Platysternon megacephalum, Gray, Proc. Zool. Soc. 1831, p. 106 ; Illustr. Ind. Zool. c. tab. Dum. 

 «f Bihr. Erpet. gen. ii. p. 345. tab. 16. fig. 6. 



Shell much depressed, truncated anteriorly and rounded posteriorly, with tlie plates 

 arranged in the same way as in the preceding genera. The sternum is rather narrow, flat, 

 joined to the upper shell by three small intercalated plates. The gular plates are very broad 

 and short, their hind margins forming a straight line ; pectorals and abdominals shorter than 

 postgulars or prseanals ; anals large, with an obtuse notch behind. 



The carapace is too small to receive the liead, legs, or tail within. The head is very large, 

 covered with a hard, horny case, flat and triangular above, broad behind, and compressed at 

 the snout. The jaws are bent anteriorly into a tooth-like hook. Tail very long, as long a.s 

 the shell, covered with rings of large quadrangular shields. 



This very singular tortoise is a native of China, probably of the southern parts, and extends 

 southwards into Pegu, where it has been found by Captain Berdmore at Schwe Gyen, on the 

 Sitang River. Although several specimens were once brought alive to Eui'ope, unfortunately 

 no record of their habits has been preserved. The larger of the two specimens in the British 

 Museum is 14 inches long, the shell measuring 5 inches in length. 



Third Family. 



THE FRESHWATER TXJKlh^^—TRIONYCIDJE. 



Shell much depressed, covered with soft skin. Feet for swimming ; toes 

 distinct, strongly webbed ; claws 3 — 3. 



Posterior sternal lobe with a broad flexible flap (valve) on each side . . . Emyda, p. 44. 



Sternum without posterior valves ; snout conically pointed Trionyx, p. 4.6. 



Sternum without posterior valves ; snout short, thick-lipped Chiti-a, j). 50. 



G Z 



