CHAP. VIII. MIGRATIONS OP SWALLOWS. 259 



in such number and variety, return to the snores of 

 Mexico and the West Indies, as to their winter home ; 

 for it is a fact not generally known, that hardly one 

 species in a hundred proceeds so far south as to cross 

 the equinoctial line. This latitude, indeed, seems to be 

 an invisible but effectual barrier to all the insessorial 

 birds of the New World ; for out of all those that have 

 been observed on the main land of North America, not 

 five are to be found in Brazil. The grallatorial and the 

 aquatic birds of the two countries are, of course, much 

 more alike ; but these, as we before observed, are wander- 

 ers, and more widely dispersed than any others. As many 

 migratory birds, like the quail, have rounded, and, conse- 

 quently, feeble wings, in capable of continued exertion, we 

 find that their journeys are performed by short stages; 

 while others, like the swallows, and their prototypes the 

 bee-eaters, rest only at the termination of their journey. 

 (271.) Among the best known of our migrating 

 birds is the swallow. Its disappearance formerly gave 

 rise to so much discordancy of opinion, that, in the 

 time of Linnaeus, the prevalent belief was, that all the 

 species of these birds retired, on the approach of winter, 

 to the bottom of ponds ; and there were even nu- 

 merous attestations to this effect. Even Linnaeus him- 

 self imbibed the popular credulity on this subject ; and 

 such was his authority, that it was a long time before 

 naturalists would relinquish the preposterous idea. It 

 is now clearly ascertained, however, that these birds 

 regularly migrate ; those few which are found dead, or 

 half dormant, during the winter, being either too feeble, 

 or hatched too late, to follow their parents. Nor, as 

 Montague justly observes, can there be any reason why 

 we should doubt their capability of performing these 

 regular migrations, when we allow it without hesitation 

 to other and much more delicate birds. In fact, the 

 swallow, from its velocity alone, is peculiarly calculated 

 for such flights ; and when we consider " that it can 

 and does suspend itself in the air for fourteen or six- 

 teen hours together in search of food, it cannot fly over 

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