BOOK X. Liv. II2-LV. 114 



sides ; but there are some that fly with their wings 

 for the greater part folded, and after giving one 

 stroke, or others also a repeated stroke, are borne by 

 the air: by as it were squeezing it tight between 

 their wings, they shoot upward or horizontally or 

 downward. Some you would think to be flung for- 

 ward, or again in some cases to fall from a height and 

 in other cases to leap upward. Only ducks and birds 

 of the same kind soar up straight away, and move 

 skyward from the start, and this even from water; 

 and consequently they alone when they have ftxllen 

 into the pits that we use for trapping wild animals 

 get out again. Vultures and tlie heavier birds in 

 general cannot fly upward except after a run forward 

 or when launching from a higher eminence ; they 

 steer with their tail. Some bii"ds tui'n their gaze 

 round, others bend their necks ; and some eat things 

 they have snatched with their feet. Many do not 

 fly without a cry, others on the contrary are always 

 silent when in flight. They move upward, downward, 

 slanting, sideways, straight forward, and some even 

 with the head bent backward ; consequently if 

 several kinds are seen at the same time, they might 

 be thought not to be travelling in the same 

 element. 



LV. The greatest flyers are the species resembling FUght oj 

 swallows called apodes" (because they lack the use of * "^'■''''' 

 feet) and by others ' cypseh.' They build their 

 nests on crags. These are the birds seen all over 

 the sea, and ships never go away from land on so 

 long or so unbroken a course that they do not have 

 apodes flying round them. All the other kinds aUght 

 and perch, but these never rest except on the nest : 

 they either hover or He on a surface. 



365 



