CHELONIA. 415 



Fam. 3. Carettochelydae. Horny shields absent, shell covered with 

 soft skin, limbs paddle-shaped, neck not retractile ; Carettochelys New 

 Guinea. 



Section 3. Trionychoidea. Mud tortoises. 



Shell flat oval and almost round, covered with soft leathery skin, without 

 horny shields, digits broadly webbed, the 3 inner digits only with claws, 

 articulation between the last cervical and first dorsal by zygapophyses 

 only, pelvis not anchylosed to shell ; 4th digit with 4 or more phalanges ; 

 marginals absent or incomplete, not joined to ribs. Head and neck re- 

 tractile, bending in vertical plane, nose as a short soft proboscis, temporal 

 fossa not roofed ; first in the Upper Cretaceous ; carnivorous, rivers of 

 Asia, Africa and N. America, in the muddy bottom of shallow waters. 

 Trionyx Geoff r., Africa, Asia, 1ST. Amer., T. ferox Schn., soft-shelled turtle, 

 U. S.A., voracious, active, edible, flesh surpassing that of the green turtle. 

 Pelochelys Gray, E. Indies ; Chitra Gray, E. Indies ; Cycloderma Ptrs., 

 trop. Afr. ; Emyda Gray, E. Indies ; Cyclanorbis Gray, trop. Afr. 



