NON-hYDIGENOUS BRITISH BIRDS. 329 



the actual shore, sometimes being very exposed in spots 

 where the vegetation is thin or not fully grown. They 

 are flat, large, and bulky structures, mere heaps of rotting 

 reeds, sedges, grasses, and rushes, with the cavity con- 

 taining the eggs lined with drier and finer material. 

 When disturbed at the nest, the sitting bird slips quietly 

 off into the water, but before leaving the eggs she care- 

 fully conceals them by covering them with weeds. 



Range of egg colouration and measurement : 

 The eggs of the Red-necked Grebe are three or four in 

 number, but sometimes as many as six. ]\Ir. Raine 

 records a clutch of the latter number belonging to the 

 Nearctic form of this Grebe. They are rough in texture, 

 elliptical in shape, and yellowish-white in colour, but 

 traces of the green interior lining frequently show upon 

 the surface. Average measurement, 2*0 inches in length, 

 by 1*3 inch in breadth. Incubation, performed by both 

 sexes, lasts from twenty-one to twenty-four days. 



Diagnostic characters : The eggs of the Red- 

 necked Grebe are smaller than those of the Great Crested 

 Grebe, and larger than those of the remaining European 

 species. The measurements may overlap, but never both 

 on the same tgg — a short Qgg is broad, a long one may 

 be narrow. 



