THE BLACK-HEADED GULL. 
163 
upper part and sides of the neck, of a lead colour ; the hill 
and legs, of a dirty, dark, purplish brown. Others have 
not the white spots above and below the eyes ; these are 
young birds. 
The changes of plumage, to which birds of this genus are 
subject, have tended not a little to confound the naturalist; 
and a considerable collision of opinion, arising from an im- 
perfect acquaintance with the living subjects, has been the 
result. To investigate thoroughly their history, it is obvi- 
ously necessary that the ornithologist should frequently 
explore their native haunts ; and, to determine the species 
of periodical or occasional visiters, an accurate comparative 
examination of many specimens, either alive or recently 
killed, is indispensable. Less confusion would arise among 
authors, if they would occasionally abandon their accustomed 
walks — their studies and their museums, and seek correct 
knowledge in the only place where it is to be obtained — 
in the grand temple of nature. As it respects, in particular, 
the tribe under review, the zealous inquirer would find him- 
self amply compensated for all his toil, by observing these 
neat and clean birds coursing along the rivers and coast, 
enlivening the prospect by their airy movements, now 
skimming closely over the watery element, watching the 
motions of the surges, and now rising into the higher 
regions, sporting with the winds, — while he inhaled the 
invigorating breezes of the ocean, and listened to the sooth- 
ing murmurs of its billows. 
