XI 



woodcocks, and many sea birds ; and those which 

 coming in spring spend their summer with us, as the 

 cuckoo, the wryneck, and the redstart : whether the 

 few species of swallow which visit us in spring, and 

 retire in autumn, are of this sort, or whether they are of 

 a nature quite different, and become torpid during winter, 

 is the question discussed in these sheets. The suspicion 

 entertained by ornithologists, that they constituted an 

 exception to the general mode of accounting for the 

 annual disappearance and reappearance of birds, must 

 have been founded on the fact of their having been 

 occasionally discovered in a state of torpidity; and it is 

 somewhat surprising that this curious circumstance did 

 not lead to an earlier knowledge of their natural his- 

 tory. The more ancient Greek bards seem to have 

 considered the swallow as a bird of passage ; while the 

 Roman natural historians regarded it as laying torpid 

 through the winter. It is more difficult to reconcile 

 their opposite opinions and evidence, by supposition 

 that some species migrate, and others lie torpid, than 

 to suppose that accidental circumstances may some- 

 times cause the torpidity of individuals of all. The 

 Greek word %eto$tov, and the Latin word hirundo, cer- 

 tainly meant the swallow; but these terms do not define 

 the species, and were probably used for swallows in 

 general; though in some instances we may, by the 

 description, discover the species which the author 



