ICELAND GULL. 
177 
and janatomical structure of any particular individual, or a 
transient observation of its habits, will often be found in- 
adequate to determine its specific rank. For example, the 
Lesser was lon^ confounded with the Greater Black-backed 
Gull, and the young of the Parasiticus described and 
figured as a distinct species. 
The rare and very interesting species of gull which 
forms the subject of this paper, seems, till lately, to have 
eluded the observation of ornithologists, and, inhabiting 
and visiting only remote regions, to have been known only 
to their rude inhabitants. But although I have myself ob- 
served it on the shores of the Baltic, and on the coasts of 
the German Ocean, it is to its occurrence in the Shetland 
Islands that my present observations are exclusively con- 
fined. In that country, possessed of so many rare facilities 
for the investigation of its zoological objects, I first became 
aware of the existence of this species, by accidentally shoot- 
ing an individual of it, in the autumn of the year 1809. 
The singularity of its appearance attracted my attention; 
and though then but a novice in ornithology, and diffident 
in indulging the hope of discovering a new species, in a 
tribe of birds so prominently exposed to the view of natu-- 
ralists, yet my curiosity was awakened, and my exertions 
to procure accurate information of its history and habits 
became indefatigable. That specimen wasj unfortunately, 
soon destroyed ; but, in 1814, I procured another, which 
I immediately afterwards presented to Mr Bui.lock, for 
his Museum in Piccadilly, and it continued to be exhibited 
there till the dispersion of that valuable collection. Its de- 
scription is the following. Length two feet nine inches, 
breadth five feet four inches, irides silver-grey, and the 
feet flesh-coloured. The general colour of the body ash, 
with a slight shade of brown ; darkest on the back, where, 
on some of the feathers, a faint tinge of blue might be per- 
VOL. IV. M 
