cuckoos' eggs and evolution, 293 



injured in anyway, as they must have been had the Cuckoo tried 

 to force an entry into them. Yet again, Mr. W. E. Wait found 

 a young Siorniculus in the nest of a Rhopocichla nigrifrons in 

 Ceylon, and this young bird, though not half-grown, completely 

 tilled the nest, into which no full-grown bird could possibly 

 have crept. 



I understand that Mr. Chance suggests that even when 

 Cuckoos do not enter nests for the purpose of laying their eggs, 

 they place themselves in such a position that they can shoot the 

 eggs by natural means into the nest direct from the oviduct but 

 this suggestion may be negatived from the fact that Cuckoos very 

 seldom smash the eggs of the tiny foster-parents with their own 

 heavy eggs, which would assuredly be the result if they adopted 

 such a method. Moreover, many nests are so placed that no 

 Cuckoo could obtain a foothold which would enable her to assume 

 a position suitable for such an action ; whilst many other nests 

 are so fragile that they would never stand the weight of an adult 

 Cuckoo hanging on to them during her acrobatic performances. 



I have dealt in this paper with only one aspect of Evolution 

 in regard to Cuckoos and their eggs but this subject opens out a 

 very wide field for observation. Thus certain recent theories of 

 '• age and area " are certainly not confirmed by a study of the 

 distribution of the CucuUdce. A.gain, many of the tenets of 

 Mendelism and the heredity of acquired characteristics seem to 

 be contradicted by the evolution of Cuckoos' eggs. But these 

 are big subjects and I merely refer to them here to show how 

 great an asset a wisely acquired collection of eggs may be in the 

 study of evolution and connected sciences. 



-EXPLANATION OF THE PLATES. 



Plate I. 

 Fig. 1. Clamator jacohinus. An oviduct egg. 



3. „ „ Ex nest of Turdoides terricolor. 



2. Turdoides terricolor. "^ 



^. Argya caudata. i-CommoniosteveistoC.JacobinusandH.varius. 



5. Turdoides griseus striatus. I '' 



6. Argya suhrufa. J 



7. Sierococcyx varitts. An oviduct egg. 



8. Clamator coromandus. Ex nest of Garrulax moniliger. 



9. Sierococcyx varius. Ex nest of Argya caudata. 



10. Grammatoptila striata. Common fosterer in extreme N.W. Range. 



11. Garrulax moniliger. 7 ^j^^ ^^^ ^^^^ common fosterers to C. coromandus. 



12. „ pectorans. ) 



Plate II. 



Fig. 1. Corvtis coronoides culminatus. (Siam.) 



3. JEudynamis scolopaceus. Prom nest of 1. 

 2. Corvus splendens insolens. (Burma.) 



4. JEudynamis scolopaceus. From nest of 2. 



5. „ „ Prom nest of 7. 



7. Corvus splendens splendens. (Beliar, N. India.) 



6. Corvus splendens protegatus. (Ceylon.) 



8. Miidynamis scolopaceus. From nest of 6. 



9. Corvus coronoides intermedius. (Assam.) 

 10. ^udynamis scolopaceus. From nest of 9. 



Proc. Zool. Soc— 1923, No. XX. 20 



