324 On the Nest and Eggs of the Common Tern 
Single Egg Nests. 
Observed i? 74, G 6B. 
Theoretical 5 74, (5 63. 
Number of brown egg layers 78"23. 
green „ 58-77. 
Number of brown egg layers with brown eggs 72'62. 
„ „ ,, with green eggs 5'61. 
Number of green egg layers with green eggs 57'39. 
„ „ „ with brown eggs 1"38. 
Two Egg Nests. 
BG G'2 
Observed 67 19 92 
Theoretical 68-92 15-15 93-93 
Number of brown egg layers 79-92. 
„ green ,, 9,8-08. 
Number of brown egg layers who lay both eggs brown 68-87. 
„ green „ „ „ 005. 
Number of brown egg layers who lay one brown, one green 10-64. 
green ,, „ „ „ 4-51. 
Number of brown egg layers who lay both eggs green 0-41. 
green „ „ „ 93-52. 
'Three Egg Nests. 
B3 B-G BG-i 
Observed 62 8 14 119 
Theoretical 59-43 13-98 9-72 11987 
Number of brown egg layers 74-30. 
gi-een „ 128-70. 
Number of brown egg layers who lay 3 brown eggs 59-43. 
green ,, „ „ O'OO. 
Number of brown egg layers who lay 2 brown and 1 green 13-77. 
green „ „ „ „ 0-21. 
Number of brown egg layers who lay 1 brown and 2 green 1-06. 
„ green „ „ „ „ 8-66. 
Number of brown egg layers who lay 3 green eggs 0-03. 
green „ ■ „ „ 119-84. 
It will be noted that the theory gives for the B^G and BG" about inverted 
proportions. It also falls short in the BG group. These would very probably 
have been bettered with a more general solution of our six equations. But are 
