184 BUTEO VULGARIS. 



of whom merely state that it varies exceedingly in colour, in- 

 somuch that two similar individuals can hardly be found, with- 

 out attempting to disclose the cause or method of this varia- 

 tion. I cannot say that I have completely solved the mystery ; 

 but the following descriptions will, I hope, be found to throw 

 considerable light on the subject. I shall begin with a pair, 

 an adult male and female shot in Ayrshire in Maj 1837. 



Male. — In size this species is rather larger than the Pere- 

 grine Falcon or Goshawk, but of a less compact form. It is 

 a robust bird, with the body full, the neck rather short, the 

 head large, roundish, and flattened above. The tarsi roundish, 

 anteriorly feathered halfway down, with twelve anterior and 

 fifteen posterior scutella, the sides covered with angular scales, 

 the digital joint, and the basal part of the toes with transverse 

 series of small scales, besides which there are on the first toe 

 four, on the second five, on the third eleven, on the fourth six 

 scutella. The toes are strong, of moderate length, the first 

 stouter, the second next, the outer proportionally much smaller, 

 and connected by a pretty large web. The claws are long, well 

 arched, and finely pointed. 



The digestive organs being in all respects as described in the 

 generic character, it may suffice here to state that the oesopha- 

 gus is six inches long, the crop three inches wide ; the sto- 

 mach two inches in diameter ; the intestine four feet four 

 inches in length, with a diameter varying from five and a half 

 twelfths to two and a half twelfths ; the coeca three twelfths 

 long ; the rectum five. 



The plumage is full and soft, rather compact and glossy 

 above ; the upper and fore part of the cere is bare, the space 

 between the bill and eye covered with bristly feathers, which 

 are slightly downy at the base ; the superciliary ridge bare, the 

 eyelids ciliated. On the head the feathers are small and lan- 

 ceolate, on the neck larger, broader, and more rounded, on 

 the back broadly ovate, on the lower parts ovato-oblong, on 

 the outer part of the leg elongated. The wings are large and 

 rounded, with tv;^enty-fivc quills, the first four primaries abruptly 

 cut out on the inner web, the first six attenuated on the outer ; 



