CYPSELUS MURARIUS. 215 



On still summer evenings, when the setting sun displays his 

 broad red disc before sinking to rest, it is interesting to see and 

 hear them screaming and hunting together as it were in packs 

 through the air, racing and chasing each other over the house 

 tops as you saunter along the Scaurs. They fly so rapidly that 

 you can hardly fancy they are hunting for prey ; yet if you 

 watch them closely a sudden turn denotes the capture of a fly. 

 When they separate they cease screaming, and, like serial 

 skaters, glide through air with rapid strokes of their tireless 

 wings. Several will sweep past as if to overtake one another, 

 and then their shrill screams form one continuous skriek of 

 delight — certainly not of fear or anger, for they are loudest 

 when close together — and never show any signs of animosity or 

 quarrelling. They revel in sultry weather and coming thunder- 

 storms, as if the electric state of the air had made them mad. 

 They may then be seen wheeling and dashing around the old 

 Castle or Cathedral ruins screaming in concert with peculiar 

 violence. At other times they rest during the day in crevices. 

 I have one in my collection which I got on opening a garden 

 door nearly opposite the Castle. It had crept in the crevice 

 between the top of the door and the lintel, and was inadver- 

 tently crushed in the opening. It only lived a few minutes. 

 To enable swifts to fly so rapidly and turn so easily, their wings 

 and tail are extremely long and narrow to fit them for catching 

 their equally agile prey ; unlike the broad concave wing of the 

 partridge or grouse, which, although they too can fly at great 

 speed in a direct line, would be useless at catching flies. The 

 wing of the swift is long and narrow, and instead of concave is 

 straight horizontally, while its humeral joint is so free that 

 when holding the bird in your hand the wing hangs loose as if 

 it were broken, while in reality the muscles are remarkably 

 strong; and while the secondary quills are very short, the 

 primaries are comparatively longer than those of any other bird, 

 and furnished with strong but elastic shafts. The tail is 

 similarly constructed — deeply forked and divided into two 

 elongated points. Also, as length of neck were worse than 

 useless in gliding through the air, the neck of the swift is so 

 extremely short that the head seems to be stuck upon the 

 shoulders, without a neck at all. And as the long pointed bill 

 were useless to pick flies in the air, like the swallows, the swift 

 merely opens its mouth, which is extremely wide and so 

 abundantly supplied with a viscid secretion, that, like an 

 unwrought spider's web, it entangles the flies and prevents their 



