The Eggs of Birds 431 



— one end blunt and narrowing to the other — that they 

 have given to it its name: oval. In the eggs of certain 

 sea-birds which breed on the narrow ledges of perpendicular 

 cliffs this oval shape is carried to an extreme, and ap- 

 parently for an excellent reason, mechanical, but of ines- 

 timable value to the birds. Eggs laid in such positions 



Fig. 343.— Egg of Murre. 



are of course especially exposed to danger from the wind 

 or from some sudden movement of the birds, which gener- 

 ally nest very close together. Were it not that the eggs, 

 on account of their peculiar shape, describe an arc of 

 very small diameter when they roll, doubtless a far greater 

 number would roll off and be dashed down upon the 

 rocks below. Among the plovers, sandpipers, and phal- 

 aropes we again find a peculiarly pronounced pyriform 



