TRIONYX. 



9 



A siiipfle neural plate between the first pair of 



costals ; pi astral callosities very feebly deve- 

 loped; alveolar surface of lower jaw witli a 



strong longitudinal ridge id the symphysis ; 



white beneath T. pJiai/rii, p. 10. 



A single neural plate between the tirst pair of 



costals ; plastral callosities well developed ; 



alveolar surface of lower jaw wdth a strong 



longitudinal ridge at the sympliysis ; Avhite [p. 11. 



beneath, young without ocellar spots T. ca)iila(/ineus, 



4. Trionyx subplanus. 



Geotft-. Ann. Mus. xiv, p. 11, pi. v, hg. 2 (1809j ; Gunth. Kept. Brit. 

 Ind. p. 49 (1864) ; Bouleng. Oat. Chelon. p. 246 (1889) ; id. Faun. 

 Brit. Ind., Kept. p. 11 (1890) ; S. Flower, P. Z. S. 1899, p. 619. 



Disk very flat and longer than broad; all the costal plates 

 separated on the median line by the uenral plates ; a single 

 neural plate between the first pair of costals ; a large fontanelle, 

 till late in life, between the nuchal and dorsal plates. Epiplastra 

 narrow ly separated from each other in front of the entoplastrou, 

 which forms an obtuse or a right angle ; plastral rugosities scarcely 

 developed, on the hyo- and hypoplastra and on the xiphiplastra 

 (these rugosities absent in the young). Dorsal skin of young with 

 interrupted longitudinal ridges. Head very large ; postorbital 

 arch extremely narrow : mandibular symphysis without median 

 ridge. Disk olive-brown or yellowish ohve above, sometimes 

 mottled all over with dark olive-brown ; young with a blackish 

 vertebral stripe and four or six small ocellnr spots, a dark oblique 

 streak behind each eye, and a A-shaped dark marking between and 

 behind the eyes ; lower parts pale lemon-yellow. 



Length of disk 250 millim. 



Mergni, Malay Peninsula, Sumatra, Borneo, Java, Pliilippines. 

 Eecorded from Penang and Singapore, and there are examples in 

 the Sekangor Museum from Terutau Island, north of Penang, and 

 from Tioman, off the coast of Pahang. A young specimen from 

 Gunong Pulai, Johore, has been referred to T. phayrii by J^ower. 



5. Trionyx hurum. 



Gray, Syn. Sept. p. 47, pi. x (1831) ; Bouleng. Cat. Chelon. p. 249 

 (1889) ; id. Faun. Brit. Ind., Rept. p. 13 (1890). 



Gymnopns gam/elicus (non Cuv.), Cantor, Journ. Asiat. Soc. Bengal, 

 xvi, p. 6i4 (1847). 



Trionyx gangeticus, Giinth. Rept. Brit. Ind. p. 47 (1864). 



Disk not or but little longer than broad ; last costal plate 

 forming a suture with its fellow ; two neural plates between 

 the first pair of costals. Epiplastra narrowly separated from 

 each other in front of the entoplastrou, which forms an obtuse or 

 a right angle; plastral callosities in the adult (hyo-hypoplastral, 

 xiphiplastral, and in old specimens entoplastral), coarsely ])itted 



