370 FORMATION OF ANIMALS. 



and this prevents its struggling and hurting the 

 dam. When the foal is born, the separation of 

 the legs takes place, but the horny substance 

 remains on the legs. In a wild state, when the 

 mares probably gallop much about to escape from 

 danger, this junction of the hind legs of the foal 

 may become still more necessary. 



Those birds whose food consists of honey ex- 

 tracted from flowers, have the tongue pencilled at 

 the tip with hairs, to which the honey adheres, 

 and which would not be the case if it was smooth. 

 Mr. Backhouse, in his interesting account of Aus- 

 tralia, mentions that the eye of the Great Night 

 Jar (Caprimulgus gracilis) is wonderfully adapted 

 for enabling the bird to see those insects in the 

 dark on which it feeds. The eye is large and 

 stretched by a bony ring of one piece, and when 

 recently removed, it forms a fine camera-obscura, 

 transmitting the images of objects facing it through 

 the integuments at the back of the retina. 



