THE IBIS 



TENTH SERIES. 



Vol. IV. No. 4. OCTOBER 1916. 



XXVIII. — On the Coloration of the Mouths and Eggs of 

 Birds ^.—11. On the Coloration of Eggs. By C. F. M. 

 SWYNNERTON, F.L.S., F.E.S., C.M.B.O.U. 



(Plate XIX. t) -'T^. 



Previous Theories. 



Hewitson wrote on the coloration of eggs in 1838, and 

 remarked the common occurrence of uniform white in the 

 eggs of species that lay in holes. I am unfortunately unable 

 to state his further views here, or Seebohm's, as, through 

 pressure of much work at the last, I left England without 

 having looked them up. Prof. Newton {' Dictionary of 

 Birds,' p. 188) says of Hewitson that "his remarks on the 

 coloration of eggs have been frequently repeated, of course 

 •with more or less modification and verbose addition, by 

 various plagiarists who have sometimes forgotten to mention 

 the source of their information." 



The only other theorist mentioned by Prof. Newton in 

 this connection is Dr. McAldowie ('*' Remarks on the 

 Development and Decay of the Pigment Layer in Birds' 



* For Part I. see pp. 264-294. 



t For explanation of plate, see p. 606. 



SER. X. — VOL. IV. 2 O 



