BIRDS AND EVOLUTION 



367 



(1914) analyses some of the peculiarities. The cerebrum 

 is greatly enlarged in front, and this may be further increased 



Fig. 57. — I, the ancestral rock-dove, Columha livia ; 2, turbit ; 3, jacobin ; 

 4, fantail ; 5, pouter. 



by hydrocephalus. But the posterior part of the cerebrum 

 is poorly developed, and this results in the formation of a 

 sort of neck which slightly separates off the cerebrum from 



