DISTRIBUTION OF ORGANISMS. 205 



either of the other two ; it is diffused over every country of 

 the globe. On the whole, it may be described as omnivorous, 

 though some genera are exclusively flesh-eaters, and even dis- 

 tinguished by their predaceous and sanguinary character. Hop- 

 ping is a prevailing, though not exclusive, mode of progression. 

 In the land genera, the foot is adapted for grasping or perching ; 

 whence the term Insessores is applied to them. The birds are 

 generally, though not in every instance, remarkable for their 

 wariness and vivacity ; some are noted for their chattering and 

 imitative powers ; some of the most advanced genera attract 

 attention by their beautiful song. 



The stirps starts with the Gulls (Larid&), an oceanic tribe 

 distributed over the whole world, of active flying habits, 

 generally of pure white plumage, presenting a variety of species, 

 some of which, as the Terns, tend to a river life, and are of a 

 swallow-like form. The mental character of the gulls does not 

 stand high in our estimate ; but we often do injustice in this 

 respect to the sea-birds, believing that to be stupidity which is 

 only unconsciousness of danger arising from the habitat being 

 remote from human haunts. Mr. Edmondstone of Zetland 

 speaks of the " characteristic inquisitiveness and vivacity" of 

 many of the gulls, being the very qualities to be expected in 

 the patriarchs of this stirps. Certain species, as the Skua, are 

 predaceous and fierce, and the Glaucous Gull is a well-known 

 attendant upon sailing vessels for the sake of offal. Like the 

 crows, the gulls attack and devour ; they will quickly eat up 

 a dead whale. The common gull, again, comes to land in 

 cultivated regions, and follows the plough in search of what it 

 may turn up. It is not unworthy of notice, considering how 

 this stirps is generally distinguished in respect of voice, that a 

 particular species of the Laridas is known, from its peculiar 

 cry, by the name of the Laughing Gull. * 



Though the Gulls are upon the whole a whitish race, there 

 are species presenting an admixture of black. This should 

 prepare us in some degree to hear the crows (Corvidce) pre- 

 sented as the immediate successors of the Gulls, more especially 

 as one of the family the Pie is chequered, and white crows 

 sometimes occur as exceptions to the rule. But the immediate 

 dependence of the colour of plumage upon conditions is one 

 of the most familiar facts of the philosophical naturalist ; and 

 the changes in this respect which individual birds undergo 

 in their moultings before attaining maturity, might well re- 

 concile us to the most startling transitions in this external 

 character. 



