INTRODUCTION. 
render its separation from tbem diiiicult. The Golden-green Ara 9 ari is assuredly a Pteroglossus; 
the Grooved-billed Ara 9 ari differs from it only in the still greater simplicity of its colouring, 
and in the greater development of those peculiar characters of the bill which show themselves 
to a certain extent in Pter. prasinus. 
If, in the preceding account of the species of Ramphastidce, I have rarely referred to the 
form of the bill as aiding in their discrimination, it is not to be attributed to any undervaluing 
of the important help to be thence derived, but to the difficulty of adequately conveying in 
words a correct idea of those varying shades of difference which are appreciable only by a 
practised eye and on direct comparison. My principal object has been to facilitate the 
ascertaining of the species of this interesting family, and I trust that I may have, to a certain 
extent, succeeded. In furtherance of the same view, I add the subjoined tabular attempt at 
a Synojms Specierum. 
