1. PLATYSTERNUM. 47 
Carapace much depressed, oval, with a feeble median keel poste- 
riorly; anterior border broadly emarginate. Nuchal shield very 
small, broader than long; vertebrals broader than long, as broad as 
or a little narrower than the costals, much broader in the young, 
in which the posterior border of the carapace is distinctly serrated. 
Front lobe of plastron squarish, posterior angularly emarginate; the 
width of the bridge contained four or five times in the length of the 
plastron; the longest plastral shields are the anals, the femorals, 
and the humerals; the shortest, the gulars, which occupy, however, 
Shell of Platysternum megacephalum. 
the whole width of the front border of the plastron; frequently a 
small intergular shield between the gulars and the humerals. Upper 
surface of head and temple with an undivided horny scute. Throat 
with round flat tubercles. Anterior face of arm with large squarish 
scutes. Hinder side of thighs with large conical tubercles. Tail at 
least as long as the shell. Carapace and soft parts of adult olive- 
brown; plastron yellowish brown. Young more elegantly marked :— 
Upper surface of head and neck and carapace olive-brown, with a 
