G12 Catalogue of Reptiles inhabiting the [July, 



Gen. Tetraonyx, Lesson, 

 Toes five ; nails 4-4 ; sternum solid, broad with six pairs of 

 shields ; 25 marginal shields. 



Tetraonyx affinis, N. S. 

 Young, Shell orbicular, its breadth exceeding its length ; the back 

 sharply keeled longitudinally, slightly arched, laterally depressed ; 

 costal shields with a tubercular nucleus at the posterior margin ; grey- 

 ish green olive, minutely spotted with brown ; edge sharply toothed, 

 pale greenish yellow. Sternum truncated in front, angularly indented 

 behind, narrow, yellow ; laterally keeled, compressed, pale yellowish 

 green. 



Habit. — Sea off Pinang. 



The outline of the shell and its composing shields strikingly resem- 

 ble the young of Cyclemys orbicitlata, Bell.* 



The nuchal shield (wanting in one individual,) is small, subrectangular 

 or subtriangular, with the base directed backwards. The vertebral shields 

 are strongly keeled, laterally sloping, hexagonal, broader than long, 

 which however with the first is less the case than with the rest ; the 

 second, third and fourth are the broadest, and of nearly equal size ; the 

 fifth assumes a broadly truncated triangular shape. The costal shields are 

 nearly all as broad as long ; the first, second and third have each a tuber- 

 cular nucleus in the centre of the posterior margin, the fourth is smooth, 

 and a little smaller than the preceding. The first pair of marginal shields 

 is truncated triangular, the second, and third subrectangular ; the fourth 

 sixth, and eighth pentagonal ; the rest subrectangular. In all, the pos- 

 terior external angle forms a more or less sharp spine, directed over the 

 anterior external margin of the next shield. From the first to the 

 sixth the shields gradually increase in size, the sixth being the largest 

 and broadest, from which the following gradually decrease towards the 

 twelfth pair, and their angular spines become obsolete. The sternum 

 consists of two parts : one central, and two lateral, formed by the sterno- 

 costal processes of the two central pairs, sharply sloping towards the 

 marginal shields. The central part is longitudinally a little concave, 

 narrowing towards both extremities, truncated in front, angularly in- 



* Syn. Emys dentata. Illust. Ind. Zoolog. — Emys dhor, Gray. — Emys hasseltii, Boie. 

 —Emys spengleri, Var. Schlegel.— Cistudo diardii, Dum. and Bibr. 



