Chap. VIL 



OSTEOLOGICAL DIFFERENCES. 



279 



A series may be formed commencing with the black- boned Silk 

 fowl, which has a very small crest with the skull beneath penetrated 

 only by a few minute orifices, but with no other change in its 

 structure ; and from this first stage we may proceed to fowls with 

 a moderately large crest, which rests, according to Bechstein, on a 

 fleshy mass, but without any protuberance in the skull. I may add 

 that I have seen a similar fleshy or fibrous mass beneath the tuft 

 of feathers on the head of the Tufted duck ; and in this case there 

 was no actual protuberance in the skull, but it had become a little 

 more globular. Lastly, when we come to fowls with a largely 

 developed crest, the skull becomes largely protuberant and is per- 

 forated by a multitude of irregular open spaces. The close relation 

 between the crest and the size of the bony protuberance is shown in 

 another way; for Mr. Tegetmeier informs me that if chickens lately 

 hatched be selected with a large bony protuberance, when adult 



Fig. 36.— Skull of Horned Fowl, of natural size, viewed from above, a little obliquely. (In 



the possession of Tegetmeier.) 



they will have a large crest. There can be no doubt that in former 

 times the breeder of Polish fowls attended solely to the crest, and 

 not to the skull ; nevertheless, by increasing the crest, in which he has 

 been wonderfully successful, he has unintentionally made the skull 

 protuberant to an astonishing degree ; and through correlation of 

 growth, he has at the same time affected the form and relative con- 

 nexion of the premaxillary and nasal bones, the shape of the orifice 

 of the nose, the breadth of the frontal bones, the shape of the post- 

 lateral processes of the frontal and squamosal bones, the direction 

 of the axis of the bony cavity of the ear, and lastly the internal 

 configuration of the whole skull together with the shape of the 

 brain. 



Vertehrce. — In O. banklva there are fourteen cervical, seven dorsal 

 with ribs, apparently fifteen lumbar and sacral, and six caudal 



