4. n.VRDELLA. 



05 



Carapace moderately depressed, with an interrupted tubercular 

 keel; margin not serrated; nuchal narrow, broadest postcriniiy ; 

 first vertebral usually narrower anteriorly than posteriorly, lateral 

 borders usually slightly sinuous ; second, third, and fourth vertebrals 

 considerably broader than long in the young, nearly as long as 

 broad in the adult. Plastron large, angulatcd laterally, truncate 

 anteriorly, angularly notched posteriorly ; the width of the bridge 



Fig. 19. 



Shell of Harddla thurgi. 



exceeds the length of the posterior lobe ; the longest median suture 

 is that between the abdominals ; suture between the gulars as long 

 as or a little shorter (at least three fourths) than that between the 

 humerals ; inguinal large, axillary smaller. Head moderate ; snout 

 short, obtuse; upper jaw notched mesially, serrated; lower jaw 

 very strongly dentated, flat iuferiorly, its width at the symphysis a 

 little less than the diameter of the orbit. Limbs with transversely 



