516 Dr. E. A. Goeldi on the 



sunset, with its head turned to the west, having by that time 

 described halt' a circle with its beak from east to west. 

 During the twelve hours of daylight its body has remained 

 in nearly the same position. 



In order to ascertain whether there was any real basis for 

 the popular notion on this subject, I made careful observa- 

 tions on a fine living specimen from the Island of Marajo, 

 which had been presented to our Zoological Gardens in 

 August 1898. I placed the bird, with a loose string tied to 

 its foot, on a large branch exposed to the full rays of the 

 sun, so that it could take the exact attitude that it would in 

 a Avild state under the same circumstances. This was done 

 on a low tree in the middle of an open place in our Botanical 

 Garden. I resolved to photograph the bird at intervals of 

 two hours during the day, so as to obtain a series of pictures 

 giving a precise idea of the bird's movements. From the 

 photographs thus obtained I have selected four which best 

 shew the relative positions of the head in life, and have had 

 them copied by our artist. 



These are given in the second series (text-fig. 1.2, p. 515), 

 nothing having been added to the originals except the sun 

 in its relative position, for the double purpose of aiding the 

 reader to realize the bird's situation in each successive 

 phase and of facilitating comparison with the first series of 

 figures. 



The first photograph, taken between 8 and 9 o'clock in 

 the morning, is reproduced in the figure on the extreme 

 right. The bird is seen wide awake, with its eyes open, 

 and not yet shewing any sign of avoiding the direct rays of 

 the morning sun. 



The second figure, photographed between 11 and 12 o'clock, 

 represents the Goatsucker in an essentially different position. 

 The sun is almost directly over its head, and has evidently 

 had the effect of making the bird turn its head away at a 

 right angle, its body remaining in the original position, its 

 eyes are closed, thus shewing its desire to avoid the already 

 unpleasant sensation of the noon-day glare. 



In the third figure is shown the result of the photograph 



