TBIO'YCHID^T];. 



Family TRIONYCHID^. 



- Carapace aud plastron without epidermal shield's, covered with 

 skiu ; marginal bones absent or forming an incomplete series, not 

 connected with the ribs ; epiplastra separated from the h^^oplastra 

 by a A-shaped entoplastron. Jaws concealed under fleshy lips ; 

 snout ending in a proboscis. Ear hidden. Head and neck com- 

 pletely retractile. Only the three inner digits clawed. 



Thoroughly aquatic, carnivorous Turtles inhabiting Eastern and 

 Southern Asia, Africa, and IN'orth America. Their ferocious 

 liabits, together with the extreme rapidity with which they 

 project their necks, render the larger individuals dangerous to 

 men bathing. Relished as food by the Chinese. 



This family is represented in the Malay Peninsula by two 

 closely related genera : — 



Postorbital arch narrower thau the orbit, which is 



nearer the temporal than the nasal fossa Trionyx, p. 8. 



Postorbital arch broad, the orbit nearer the nasal 



than the temporal fossa ; proboscis very short . . Pelochelys, p. 11. 



Genus TRIONYX. 

 Geoftr. Ann. du Mus. xiv, p. 1 (1809). 



Plastron without cutaneous valves, the limbs remaining com- 

 pletely exposed ; dorsal disk without marginal ossifications. Bony 

 ohoanse between the orbits ; jaws strong ; postorbital arch narrower 

 than the diameter of the orbit. Tail very short. 



Eastern and Southern Asia, Africa, JSTorth America. 



Eggs spherical, hard-shelled. 



Malay generic name, Labi-lahi. 



Kiijnopsis of the Sj^ecies. 



I. All the costal plates separated on the median 



line by the neural plates ; disk longer thau 

 broad ; pi astral rugosities scarcely deve- 

 loped : head ver}' large ; young without or 

 with small ocellar spots T. suhplanus, p. 9. 



II. Last pair of costal plates in contact on the 



median line; head moderately large; no 



dark vertebral stripe. 

 Two neural plates between the first pair of costals ; 

 plastral callosities very large in the adult ; 

 alveolar surface of lower jaw flat or with a 

 longitudinal furrow at the symphysis; olive- 

 brown beneath, young with 4 or 6 large ocellar 

 spots on the back T. hurmn, p. D. 



