Chap. VII. 



OSTEOLOGICAL DIFFERENCES. 



275 



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 extraordinary. First for nine skulls of dif- 

 ferent sub-breeds of English Polish fowls. The hemispherical pro- 

 tuberance of the frontal bones u8 may be seen in the accompanying 



B 



Fig. 31.— Skulls of natural size, viewed from above, a little obliquely. A. Wild Callus 



bankica. B. White -created Polish Cock. 



drawings, in which (B) the skull of a white-crested Polish fowl is 

 shown obliquely from above, with the skull (A) of G. bankiva in the 

 same position. In fig. 35 longitudinal sections are given of the 

 skull of a Polish fowl, and, for comparison, of a Cochin of the same 

 size. The protuberance in all Polish fowls occupies the same position 

 but differs much in size. In one of my nine specimens it was ex- 

 tremely 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 oj)en pore ; 



68 See Mr. Tegetmeier's account, 

 with woodcuts, of the skull of Polish 

 fowls, in ' Proc. Zoolog. Soc.,' Nov. 

 2")th, 1856. For other references, see 

 Isid. Geoffroy Saint- Hilaire, ' Hist. 

 Gen. des Anomalies,' torn. i. p. 287. 



M. C. Dareste suspects ('Kecherches 

 sur les Conditions de la Vie,' &c, 

 Lille, 1863, p. 36) that the protuber- 

 ance is not formed by the frontal 

 bones, but by the ossification of the 

 dura mater. 



