Birds. 1495 



exception of the crane, it is certainly the most lofty as well as 

 the most vigorous flyer of the Australian birds. I have frequently ob- 

 served in the middle of the hottest days, while lying prostrate on the 

 ground with my eyes directed upwards, the cloudless blue sky peo- 

 pled at an immense elevation by hundreds of these birds, performing 

 extensive curves and sweeping flights, doubtless attracted thither by 

 the insects that soar aloft during serene weather ; hence, as I have be- 

 fore stated, few birds are more difficult to obtain, particularly on the 

 continent of Australia, where long droughts are so prevalent ; on the 

 contrary, the flocks that visit the more humid climate of Van Die- 

 men's Land, where they necessarily seek their food near the earth, are 

 often greatly diminished by the gun during their stay. 



" I regret that I could ascertain no particulars whatever respecting 

 the nidification of this fine bird, but we may naturally conclude that 

 both rocks and holes in the larger trees are selected as sites for the 

 purpose, as well as for a roosting-place, during the night. Before re- 

 tiring to roost, which it does immediately after the sun has gone 

 down, the Spine-tailed Swallow may frequently be seen either singly 

 or in pairs sweeping up the gullies, or flying with immense rapidity 

 just above the tops of the trees, their never-tiring wings enabling them 

 to perform their evolutions in the capture of insects, and of sustain- 

 ing themselves in the air during the entire day without cessation. 

 The sexes offer no perceptible difference in their outward appearance; 

 but the female, as is the case with the other members of the family, is 

 a trifle smaller than her mate. 



" Crown of the head, back of the neck, and ear-coverts deep shining 

 green, strongly tinged with brown ; a small space immediately before 

 the eye deep velvety black ; and across the forehead, throat, inner 

 webs of the secondaries nearest the back, a patch on the lower part of 

 the flanks and the under tail-coverts white ; wings and tail deep shin- 

 ing green, with purple reflexions ; centre of the back grayish brown, 

 becoming darker towards the rump ; chest and abdomen dark clove 

 brown ; bill black ; feet brown. 



" The figures are those of the male and female of the natural size." 



It is interesting that the singular genus Acanthylis, or Spine-tailed 

 Swallow, occurs in North and South America, on the continent of In- 

 dia, in New Holland, and now in Europe. The type of the genus, 

 the Acanthylis pelasgia, is a smaller bird than the present, is a native 

 of North America, and is figured in Wilson's c American Ornithology,' 

 pi. xxxix. fig. 1. I was at first induced to believe, that the bird now 

 under consideration would turn out to be the North American species, 



