(d) 



Fig. 12. 

 Diagrams of the lungs of tetrapods to show the increase in the 

 infolding of their surfaces, (a) Proteus, (b) Siren, (c) Rana (d) 

 Sphenodon, (e) Varanus (a lizard), (f) Thassochelys (a turtle) (g) 

 Chamaeleo. 



