BY D. EMBLETOX, M.D. • 67 



Thus, in the egg of the Emu, the innermost layer of the shell is 

 white, the next pale green and more crystalline, further out the 

 colour deepens, whilst on the external surface there is an irre- 

 gularly reticulated coating of a very dark, varnish-like, opaque, 

 deep olive green, the ridges having a fine polish. 



In the eggs of the Peewit and Guillemot the innermost layer is 

 white, the middle part, in many, very pale green, and the layers 

 external to this are white, yellow, blue, or green, spotted more 

 or less with dark red or brown, and the surface is the same. 



In those of the Thrush a thin white layer lies next the mem- 

 hrana putaminis, and the delicate greenish blue, characteristic of 

 this Qgg, succeeds. The same white internal layer exists in the 

 egg of the Blackbird. In both of these cases the spotting, when 

 it occurs, is confined to the external surface. In Mr. J. Han- 

 cock's ''Catalogue of the Birds of I^orthumberland and Dur- 

 ham," published in the ISTat. Hist. Trans, of JSTorth. and Durh., 

 Yol. YI., 1874, we find it stated, that ''the eggs of the true 

 Falcons can be readily distinguished from those of the ignoble. 

 Those of the former are of a pale yellow colour when held up 

 to the light and looked at from the interior of the shell. Those 

 of the Eagles, Buzzards, Hawks, etc., when examined in the 

 same manner, are of a pale green hue." 



In the case of the Greater Black-backed Gull, the innermost 

 layer is of a dull white, those external to it are of a purer white, 

 crystalline and granular in texture, and mottled here and there 

 with dusky spots like those of the exterior. 



In many spotted or blotched eggs the spots or blotches are not 

 confined to the surface but exist in several of the subjacent layers; 

 and those near the surface show through the outermost coating, 

 more or less imperfectly, as in eggs of the Scolopacidm, the inner- 

 most layer being, as already stated, more or less pure white, or 

 of the colour of the albumen. 



Examples of all the above named, and of many other varieties, 

 are easily to be met with in any good collection of eggs. Those 

 which have here been noticed may not all be found in a small 

 collection, but they are to bo seen in the collections to which I 

 have had access, namely, to that of the Natural History Society 



