476 OBSERVATIONS ON SOME SPECIES 
naturalists, his contemporaries, as well as others whose 
works were published after his death, were inclined to 
doubt the accuracy of this opinion, rather regarding it as 
the female of the Mergus merganser^ or Goosander ; yet 
without bringing forward any positive proof of the accu- 
racy of their own opinion, or of the fallacy of that of Lin- 
N^us. In the thirteenth edition of the Sy sterna Natur<z^ 
they are held as distinct ; but the many inaccuracies in that 
edition, as compiled by Gmelin, render it very slightly 
authoritative in any disputed point. The same opinion, 
however, being maintained, and its accuracy apparently 
well illustrated by Dr Hey sham, from personal experience 
and observation^ it was received by Latham and Mon- 
tagu, and, accordingly, the Dundiver and Goosander are 
described as distinct species in their respective works. The 
French naturalists, on the other hand, in conformity with 
an old opinion of Buffon's, have recently preferred follow- 
ing the idea of their being the same, and, as such, they are 
united in the latest Parisian system, the Regne Animal of 
CuviER. As, however, there are no additional reasons as- 
signed in support of this opinion, nor any facts or series of 
observations related, from which it may be supposed to have 
resulted, — those who regarded these birds as distinct, saw 
no reason to alter their sentiments, or to resign one belief, 
however unsupported, in faV^our of another, which was 
equally so. In short, the matter remained precisely as it 
was fifty years ago. 
In the absence of special facts applicable to any parti- 
cular species, the history of which we wish to illustrate, I 
conceive the next safest rule to be, to proceed upon the 
analogies observable among other nearly allied species of 
the same genus. As, for example, with the species now 
under consideration : Two birds, entirely dissimilar in re- 
spect to plumage, are alleged to be distinguished from each 
