EXPLANATION OF PLATES IV & V^contiriued. 



Fi&. 12. — Single longitudinal section, showing junction of ilium, pubis, and 

 pectineal process ; sis days' chick ; length of hind limb 0'2 in. 



Fig. 13. — Pelvic girdle of Emys europaea (from Hoffmann). 



Fig. 14. — „ Cyclodus gigas; right side. 



Fig. 15.— 

 Fig. 16.— 

 Fig. 17.— 

 Fig. 18.— 



chick on sixth day of incubation. 

 Laosaurus (from Marsh). 

 Ornithorhynchus ; right side, 

 chick ; twentieth day of incubation. 



(The shading denotes ossification ; the unshaded parts are still cartilaginous.) 



