4, HARDELLA. 65 
Carapace moderately depressed, with an interrupted tubercular 
keel; margin not serrated; nuchal narrow, broadest posteriorly ; 
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, angulated laterally, truncate 
anteriorly, angularly notched posteriorly ; the width of the bridge 
Fig 19. 
Shell of Hardella 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 inferiorly, its width at the symphysis a 
little less than the diameter of the orbit. Limbs with transversely 
