PUFFIN. 317 



colonies at St. Kilda was perfectly overwhelming', and 

 can never be forgotten. 



Range of egg colouration and measurement : 

 The Puffin lays only one egg, which will, however, be 

 replaced several times if taken. It is dull white, some- 

 times tinged with very pale blue or gray, in ground 

 colour, very obscurely spotted, blotched, and occasionally 

 streaked with pale brown, and with underlying markings 

 of gray. As a rule the latter type of markings prevails, 

 and very often both kinds form a zone round the larger 

 end of the egg. So dirty, however, do the eggs become 

 through contact with the wet feet and plumage of the 

 parent birds and the soil of the burrow, that little, if any, 

 of the pale markings are visible until they have been well 

 washed. Average measurement, 2*4 inches in length, by 

 I '65 inch in breadth. Incubation, performed by both 

 sexes, lasts about five weeks. 



Diagnostic characters : The ^gg of the Puffin is 

 readily identified by its size, pale ground colour, and very 

 indistinctly defined markings. 



Family PROCELLARIID^. - . Genus Procellaria. 



LEACH'S FORK-TAILED PETREL. 



Procellaria leachi, Temminck. 



Single Brooded. Laying season, June. 



British breeding area : The known breeding- 

 places of the Fork-tailed Petrel within our area are 

 remarkably few, but there can be no doubt whatever 

 that many more will eventually be discovered on the 

 western coast-line, notably amongst the Hebrides. It 



