Vol. xlii.] 40 



A closer study of the eggs reveals many interesting points ; 

 they appear to be in the transition-stage, i. e. there is a 

 distinct tendency for them to become more conspicuously 

 surface-marked. This theory is based on the following 

 experience. In 1919 these eggs were collected in large 

 quantities for food, and I had the opportunity to examine 

 some hundreds from Barra. There was scarcely an egg 

 among them that was not well marked. I was so struck by 

 this interesting fact that I got into communication with the 

 collectors who had gathered Puffins' eggs for many years, 

 and I found they had alreadj' noticed these well-marked eggs, 

 mentioning that the eggs the}' collected 80-35 years ago were 

 nearly all unmarked. Many of the eggs figured in different 

 works are well marked. It is probable, however, that these 

 were selected for the purpose, and are not typical of the eggs of 

 that time. My own experience is that they were then mostly 

 white and almost unmarked, or rather the markings were 

 much deeper, i. e. covered by a thicker lime layer. Puffins' 

 eggs are nearly all well marked ; this can be proved by 

 holding the eggs to a strong light and looking through the 

 blow-hole, or by scraping away the outer lime layer until the 

 pigment is reached. As an illustration I have treated in this 

 way half of one of the eggs exhibited in a longitudinal 

 direction, varnishing this part to bring out the density of the 

 pigment ; the other half is left normal to show the deep- 

 lying markings. 



Among those exhibited will be found one egg with large 

 superficial markings on the large end, the underlying mark- 

 ings being almost absent. Another has a large superficial 

 n)ark measuring 20 x 15 mm. A third egg from the Fames 

 is heavily peat-stained dark brown. 



Many eggs show a distinct tendency towards erythrism ; 

 the buff and cream ground eggs when held to strong light 

 show through reddish ; the type-eggs have a brownish inner 

 liuie layer. 



Similar rudimentary characteristics may be found in the 

 eggs of the Barred Warbler {S. nisoria), certain forms of 

 Nightjar {C. europtvus), Grifibn-Vulture ((r. fulvus), aud the 



