BIRDS 129 



It seems to me unlikely that the pollex should have existed 

 between this tubercle and the excrescence on the radius, as it 

 would have done according to Messrs. Newton's description. 

 These authors state that the tubercle sometimes projects 

 downwards rather than laterally, and is always more or less 

 pedunculate. As far as I can judge from the skeleton 

 mounted in the Natural History Museum (British), this 

 means that the tubercle projects from the anterior or outer 

 edge of the bone, and a little downwards or inwards ; 

 certainly in this skeleton the tubercle is larger towards the 

 inner side when the wing is folded, and it shows an incipient 

 division into two parts. The metacarpal is shorter and 

 thicker than in ordinary birds. 



The radius is much thicker and stouter than in ordinary 

 birds, and bears at its distal end on the anterior edge a 

 rugged excrescence or exostosis, similar in appearance to the 

 tubercle on the metacarpal, and evidently associated with the 

 latter in function and development, but not so prominent 

 and not pedunculate. 



In the female the radial exostosis is absent, and the 

 metacarpal either absent or much smaller than in the male. 



There can be little doubt that these exostoses were used 

 in fighting by the males, and that, therefore, the facts are in 

 harmony with the view that their unisexual development is 

 explained by unisexual irritation of the bones affected. But 

 the subject is worth examining in more detail. Everyone 

 has seen domestic pigeons occasionally buffeting each other 

 with their wings, but their fights are not very violent, nor of 

 long duration. They naturally, however, suggest the supposi- 

 tion that the male Solitaires fought in a similar way, but it 

 seems to me that if this had been the case the exostoses 

 would have been on the outer or dorsal surface of the wrist 

 and not on its anterior edge. The actual position of the 

 principal tubercle indicates that, if it was used offensively, 



