54 



BowDiSH, Abnormal Bill of MeUnierpes portoriccnsis. 



TAuk 

 Ljan. 



mal female, possessed a beak abnormally developed in a most 

 interesting manner. An injury near the base of the lower man- 

 dible, partially breaking it away, as a shot might do, seems to 

 have caused this growth. 



The theory that I have evolved to account for it, is that as the 

 wound healed the edges contracted, warping the mandible toward 

 that side and tending to the corkscrew-shaped growth that the 

 mandible exhibits. The bird was debarred from hammering by 

 the weakened and misshapen bill, and the growth which normally 

 would have replaced wear, abnormally prolonged both mandibles, 

 though why the lower so much more than the upper I cannot 

 readily understand. 



The measurements of this bill are : length of upper mandible, 

 (exposed culmen), 1.33 in.; lower mandible from symphysis, 1.85 

 in. ; width at base, .34 in. 



The extent of the abnormal growth can be better appreciated 

 by a comparison of a table of measurements of bills of nine spec- 

 imens in my collection : 



This table shows the average length of the upper mandible to 

 be about i.oo in.; length of lower mandible, .67 in.; and the 

 width of bill at base .;^t,. Thus it will be seen that in the spec- 

 imen under consideration, while the width of the base of bill is 

 about normal, the upper mandible is a third of an inch longer 

 than the average, and the lower nearly three times the average of 

 these nine specimens. 



The illustrations show very well the form of the beak. It will 

 be noticed that the lower mandible makes a half turn, so that 

 what should be its lower surface is, at the tip, the upper ; while 



