OSTEOLOGY OF BIRDS 



185 



men, and altogether absent in the hen. Thus we have four pairs 

 of ribs that connect by others with the sternum, and I must believe 

 this to be the normal arrangement in the case of the species before 

 us. Darwin has amply shown that it varies widely in many of the 

 domesticated fowls, and from his and my own studies, 1 am in- 

 clined to believe that the time will come when there will appear 

 domesticated races of fowls in "which all the vertebrae in the adult, 

 from atlas to pelvis inclusive, will remain free segments, and 

 coossification in the dorsal region will not occur. G . b a n k i v 'i 

 also normally possesses " sacral ribs," which spring from the lead- 

 ing fused vertebrae of the pelvic sacrum, are long and slender, and 

 without uncinate processes. At their lower ends they articulate 

 with haemapophyses. Each one of these latter bones has a much 

 expanded and laterally compressed posterior extremity, while an- 

 teriorly its end articulates with the hinder margin of the ultimate 

 haemapophysis, at a short distance above the costal border of the 

 sternum of the corresponding side. Briefly recapitulating then, we 

 find that G . bankiva normally possesses seven pairs of ribs ; 

 the first two pairs fail to connect with the sternum, while they do 

 in the case of four pairs that succeed them ; finally there is a 

 seventh, or sacral pair, which articulates below with what may be 

 called a pair of " floating ribs," not using, however, this latter term 

 quite in its anthropotomical or even crocodilian sense. 



Perhaps of all the larger bones of the axial skeleton, the pelvis has 

 retained its primitive form more than any other among the many 

 domesticated breeds as compared with that bone in the original stock 

 of them all, the G . bankiva at my hand. I felt that my work 

 upon this part of the skeleton was more than half accomplished 

 when I completed the drawings in figures 13, 14 and 15, and yet 

 how little the last named one differs from Parker's figure of the 

 pelvis in the common barnyard fowl I 1 



To be sure Darwin found that the anterior margin of the ilium 

 varied from a rounded to a truncate outline; that the extremity of 

 the pubic bones were " gradually enlarged in Cochins, and in a 

 lesser degree in some other breeds ; and abruptly enlarged in 

 Bantams." [Animals and Plants under Domestication, p. 324 ] 



Careful count assures me that there are 15 vertebrae included in 

 the consolidated pelvic sacrum, of which the first four throw out 

 their diapophyses to abut against the nether surface of the ilium 

 upon either side. In both of my specimens the propubis is very 



1 See Encycl. Brit., ed. 9, p. 722, fig. 34, and numerous copies elsewhere. 



