HYBRIDISM AMONG COCKATOOS. 19 



We see from this that the hybrid in these characters, just 

 as in the case of the incommensurate characters tabulated on 

 p. 16, stands nearer to the male than to the female. Of 

 course, the actual ratio thus arrived at can be regarded only 

 as the very roughest appi'Oxin)ation, since we are dealing with 

 a single specimen of the hybrid. 



The only examples of hybridism among the Psittacidas 

 that have been traced in the available literature are those 

 quoted by Hans Przibram.^ 



"Macaws: Ara macao (^ and A. militaris ?, one 

 young rather similar to militaris, died early. 



"Parakeets: Platycercus pallidiceps (J and PI. 

 eximius (Roselle Parakeet) ?; also, Platycercus exi- 

 mius cJ and PI. pennantii ? ." 



From the remark under macaws it would appear that the 

 characters of militaris tend to be prepotent over those of 

 macao. In this case it will be noticed that it was the 

 female which was prepotent, while in the present example of 

 the cockatoos it was the male. 



An interesting point in this connection is whether the 

 prepotency of the male-parent in this case was due to the 

 stronger inheritable nature of the Cacatua characters than 

 of the Lie metis characters, or whether the prepotency was 

 in some way connected with the male sex or with the indi- 

 vidual specimen. To test this point it would be of great 

 interest to obtain hybrids with male Lie metis and female 

 Cacatua. 



Przibram,'^ in his recent work, has compiled a considerable 

 list of cases of hybridism, and has illustrated a good number 

 in a series of sketches. In many examples the hybrid is 

 represented as being very strikingly intermediate between 

 the two parent forms in all the general characters depicted. 

 As far as can be seen, a very thorough blending of characters 

 has mostly occurred, and from a general inspection it is often 



' Przibram, Hans, ' Experimental-Zoologie. Phylogenese,' p. 89, 

 1910. 



2 Ibid., p. 89. 



