262 



FOWLS. 



Chap. VII. 



bones, which are rather short, and between these branches and the nasal 

 bones. The surface of the frontal bone, on which the branches of the 

 premaxillary rest, is very little depressed. These peculiarities no doubt 

 stand in close relation with the broad flattened rose-comb characteristic 

 of the Hamburgh breed. 



I have examined fourteen skulls of Polish and other crested breeds. Their 



differences are ex- 

 traordinary. First 

 for nine skulls of 

 different sub-breeds 

 of English Polish 

 fowls. The hemi- 

 spherical protuber- 

 ance of the frontal 

 bones 08 may be seen 

 in the accompany- 

 ing drawings, in 

 which (B) the skull 

 of a white -crested 

 Polish fowl is shown 

 obliquely from a- 

 bove, with the skull 

 (A) of G. oanhiva 

 in the same position. 

 In fig. 35 longi- 

 tudinal sections are 

 given of the skulls 

 of a Polish fowl, 

 and, for comparison, 

 of a Cochin of the 

 same size. The protuberance in all Polish fowls occupies the same posi- 

 tion, but differs much in size. In one of my nine specimens it was 

 extremely slight. The degree to which the protuberance is ossified varies 

 greatly, larger or smaller portions of bone being replaced by membrane. 

 In one specimen there was only a single open pore ; generally, there are 

 many variously-shaped open spaces, the bone forming an irregular reti- 

 culation. A medial, longitudinal, arched ribbon of bone is generally 

 retained, but in one specimen there was no bone whatever over the 

 whole protuberance, and the skull when cleaned and viewed from above 

 presented the appearance of an open basin. The change in the whole 

 internal form of the skull is surprisingly great. The brain is modified 

 in a corresponding manner, as is shown in the two longitudinal sections, 



Fig. 34. — Skulls of natural size, viewed from above, a little obliquely. 

 A. Wild Gallus bankiva. B. White-crested Polish Cock. 



08 See Mr. Tegetmeier's account, with 

 woodcuts, of the skull of Polish fowls, 

 in ' Proc. Zoolog. Soc.,' Nov. 25th, 1856. 

 For other references, see Isid. Geoffroy 

 Saint Hilaire, ' Hist. Gen. des Ano- 

 malies,' torn. i. p. 287. M. C. Dareste 



suspects (' Kecherches sur les Conditions 

 de la Vie,' &c, Lille, 1863, p. 36) that 

 the protuberance is not formed by the 

 frontal bones, but by the ossification of 

 the dura mater. 



