5214 MR MACGILLIVARY ON THE 
in the essential qualities enumerated, cannot with any pro- 
priety be used, should a method possessed of those quali- 
ties be pointed out. It is the difficulty of finding such a 
method, more than the conviction that the present one is 
the most ehgible, that would appear to induce ornithologi- 
cal writers to adhere to this mediod. * 
Enough, I imagine, has been said on this subject : it re- 
quires Httle ingenuity to shew the futihty of what every 
body acknowledges to be futile, however much it may re- 
quire to persuade men to abandon a practice established 
by authority, and sanctioned by habit. The observations 
made would be of little importance, were they not intended 
as introductory to a method of characterising the species of 
birds, which shall presently be announced. With this ob- 
ject in view, a few more remarks may not be altogether im- 
proper. 
And first, it is necessary to advert to the colour of the 
iris (some have even gone so far as to notify the colours of 
the down and even of the skin ; all which is very becoming 
in the way of description, but can have little to do with 
specific distinction), which may be thought to merit parti- 
cular attention. The colour of the iris forming a character, 
belonging to a very delicate part, which is the most easily 
altered by the action of the air, and by other causes, after 
death, is seldom in a condition to be examined by the time 
that a specimen comes to the hands of a naturalist. From 
my own experience, I can say little more on this subject 
than merely, that, being precisely in the same predicament 
with the colour of the feathers, it must necessarily share 
the same fate. This conclusion is corroborated by the expe^ 
rience of Mr John Wilson, who will be found to possess 
a stock of practical information in ornithology, which, 
in a matter of fact, entitles him to much more credit 
