2l6 



STUDIES IN THE EVOLUTION OF ANIMALS 



that the ears of the Rhinoceros and the Armadillo are singularly 

 alike. Then if we turn to fossils, we find that the Polacanthus has 

 a bony pelvic shield rising in knobs/ not unlike those of the hide- 

 shields of the Indian Rhinoceros (Fig. "j-j^ This is what Nicholson 

 and Lydekker say of it (p. 1161): 'In Polacanthus of the same 

 (Wealden) beds, we have a remarkable form (of Dinosaur), in which 

 the dermal armour constitutes a complete solid carapace over the 



Fig. 77. — Indian Rhinoceros [R. Unicornis), from a photograph, F. G. O. S. 20046. 



whole of the dorsal aspect of the lumbar regioTi, some of the com- 

 ponent scutes being tuberculated, and others ridged ; while there 

 was also a number of detached flattened spines somewhat like 

 those of Hyseosaurus, which probably formed a line in the dorsal 

 region. This peculiar type of carapace forcibly recalls that of the 

 Glyptodont edentates.' 



In order to emphasise the similarity of the Rhinoceros and the 

 1 See Fig. 63 (a). 



