Families LARIDAE and STERNIDAE. 

 (Plates 160—180). 



LARUS ARGENTATUS BRUNNICH. 



Dr. G. a. Venema ') wrote as follows about the difference in the 

 colour of the shell of argentatiis-eggs: 



„ ... It will, I am sure, not be considered strange if I declare that I regard 

 „the difference in the colour of the shell of the eggs to be dependent on the 

 „nature of the food. The Herring-Gull eats small fishes by preference, which 

 „in mild weather, if it is not blowing too hard, it catches in the shallows, 

 „or which it is able to find in the crests or hollows of the waves. The food 

 .which it considers ^tastiest is young flounders, plaice, and sole which in 

 „many instances are born in the shallows to be trained there for the turbulent 

 „life at sea, and hence the Herring-Gull visits fishermen at sea when they are 

 „drawing in their nets and it likes to follow shoals of rapacious fish, as they 

 pCause the small fishes on which they prey to flee to the surface. When this 

 „fish food is eaten the eggs which the Herring-Gull lays acquire a very 

 JigM blue colour. 



„lf in the breeding season the weather is cold and bleak the young flatfishes 

 „do not venture into the upper layers of the brackish or salt water but hide 

 „in the depths below. The Herring-Gull which cannot reach them there and 



') See his article: „Over het eiland Rottum", occurring in: „Bijdragen tot 

 de kennis van den tegenwoordigen staat der Provincie Groningen", Vol. IV 

 (Groningen, 1869), p. 400 et seq. 



