BRITISH ZOOLOGISTS. 119 



warmer region. On the contrary, he clung to the widely- 

 spread belief that 'many of the swallow kind do not 

 depart from this island, but lay themselves up in holes 

 and caverns, and do, insect-like and bat-like, come forth 

 at mild times, and then retire again to their tatebrce or 

 lurking-places.' To this idea he recurs again and again ; 

 and he does not even appear to be quite clear, but that 

 the popular northern notion that swallows in autumn 

 bury themselves in the mud at the bottom of streams 

 and ponds may not have some truth in it. He seems to 

 have corresponded much with Pennant as regards this 

 qu&stio vexata ; and the latter devotes considerable space 

 in his 'British Zoology' to a discussion of the evidence 

 on the point. Pennant's own conclusion was that the 

 greater portion of the swallows migrate to some warmer 

 country, but that the late broods, being unfit for so 

 arduous a journey, hybernate in this country. We are 

 obliged, says Pennant, to conclude that ' one part of the 

 swallow tribe migrate, and that others have their winter 

 quarters near home. If it should be demanded, why 

 swallows alone are found in a torpid state, and not the 

 other many species of soft-billed birds, which likewise 

 disappear about the same time? the following reason 

 may be assigned : 



' No birds are so much on the wing as swallows, none 

 fly with such swiftness and rapidity, none are obliged to 

 use such sudden and various evolutions in their flight, 

 none are at such pains to take their prey, and we may 

 add, none exert their voice more incessantly; all these 

 occasion a vast expense of strength and of spirits, and 

 may give such a texture to the blood, that other animals 



