CUCULUS CANORUS L. 



observations, come to the conclusion that the period in which eggs 

 are laid may be estimated at about 48 days, during which an egg 

 is laid every six days, and every female bird therefore produces 8 

 eggs at the most in one season. The high number of 20 in one 

 season, which Dr. Rey *) assumes to be the case, is, in Link's opi- 

 nion, founded on an error: „Der Irrtum des Dr. Rey erklare sich 

 „dadurch" — Link writes — „dass er die Eier von mehreren Weib- 

 „chen fur die von einem einzigen Weibchen gelegten halte. In jeder 

 „Gegend, namentlich in denen, wo viele Kuckucke vorhanden waren, 

 „finde man Weibchen, die alle ganz gleiche Eier legten, so dass 

 „man die Eier der verschiedenen Weibchen nicht unterscheiden 

 „konne." The words „ganz gleiche" should of course be taken cum 

 grano salis; namely in the sense of „belonging to one type", there- 

 fore in conformity with Latter's 2 ) hypothesis that it is highly 

 probable that tribes of closely allied co/zon/s-individuals exist of 

 which the female birds lay eggs of one and the same type, and the 

 greater part of which pay attention exclusively to their own parti- 

 cular species of foster parents. 



In 1831 Schlegel 3 ) wrote: „The female bird begins to lay 

 „early in June. She goes on doing so till the middle of July. In the 

 „case of this bird the eggs develop very slowly, namely with inter- 

 nals of from six to eight days." 



1 ) Altes und Neues aus dem Haushalte des Kuckucks. Leipzig. 1892. 



2 ) 1. c. page 53. The article itself is to be found in „Biometrika", vol. I, 

 part II (1902). 



s ) Verhandeling ter verklaring der redenen, waarom de Koekoek geen nest 

 maakt, en zijne Eijeren niet zelf uitbroedt. (Essay in explanation of the 

 reasons why the Cuckoo does not build a nest, and does not hatch its eggs 

 itself). (Natuurk. Verh. v. d. Holl. Maatsch. der Wetensch. te Haarlem, 19e dl. 

 Haarlem, 1831). 



