88 Monograph of the Oranes. 



approaching them they evince more curiosity than timidity, looking down 

 at the slightest noise, and apparently more anxious to obtain a full view of 

 the intruder than for their own safety. They are almost invariably in pairs, 

 and both birds can generally be secured." 



I have seen and examined the tracheae sent by Prof. Grarrod's correspon- 

 dent, but, being in a dry state, they do not give so good an idea of the 

 wonderful complexity of the convolutions as the following woodcut, reduced 

 from a lithograph accompanying an article by Professor Pavesi, of the 



OONTOLUTIONS OF TeAOHBA ON THE BkBAST OP KeEADDHBN's CeOW ShEIKB. 



University of Genoa, which appeared in the " Annali del Museo Civioo," 

 vol. vi. 



That a bird the size of a missel-thrush should be able to produce a sound 

 so loud as that described is, I think, a conclusive proof that the effect of 

 the elongation and convolution of the trachea is the deepening of the tone 

 and the increase of the loudness of the voice, which is the proposition that 

 I have endeavoured to demonstrate; bat why certain birds should require 

 such a deep-toned and far-reaching voice, which is not possessed by closely 

 allied species, is a matter still to be determined. 



