R. S. Lull — Cranial Musculature in Dinosaurs. 397 



impression of a mental capacity far beyond the actual size of 

 the brain. In each case the large, seemingly massive skull is 

 composed of extensive plates of bone bridging over cavernous 

 spaces within, giving great superficial extent for mechanical 

 needs with comparatively little expenditure of osseous material. 



■rs-l 



Fig. 8. 

 Fig. 9. 



Iguanodon bemissartensis ; adapted from Dollo. 

 Trachodon mirabilis ; after Cope. 



Jfeiolania, a chelonian from the Pleistocene of Lord Howes 

 Island and Queensland, has even developed horns, at first sight 

 extremely suggestive of those of the Ceratopsia though situated 

 too far back over the occiput for a precise homology. 



The most interesting instances of convergence are with the 

 chameleons, the likeness of whose casque to the Ceratopsian 

 crest has been emphasized. The Dwarf chameleon C. pumilis 



Am. Jour. Sci.— Fourth Series, Vol. XXV, No. 149.— May, 1908. 



27 



