BY D. EMBLETON, M.D. 65 



In different genera and species, and in different individuals 

 almost innumerable varieties of form occur, the same bird indeed 

 will, even in the same nest, lay eggs differing greatly in form. . 



The size, also, as well as the form of eggs, is similarly varied. 

 Indeed, I ha-ve the authority of Mr. John Hancock for saying 

 that there are never two eggs exactly alike in these respects. 



The largest eggs known are those of the Dinornis of IN'ew Zea- 

 land, and the Epiornis of Madagascar, both extinct birds. The 

 egg of the Dinornis measures eight inches and a half in length, 

 and that of the Epiornis thirteen inches. They are both un- 

 spotted, and of beautiful oval form. 



The smallest, of the size of a small pea, are those of some 

 Humming Birds. 



These then are established facts, and we can see how in all pro- 

 bability different forms arise, but why they should so differ is 

 another question. Why, for instance, should a Guillemot lay a 

 pyriform egg that will not readily roll off the narrow bare ledge 

 of smooth rock on which it is laid, whilst a Plover drops an egg 

 of similar form into a concave and safe nest out of which it can- 

 not roll, and which is placed on the surface of a ploughed field 

 or on a moor ? 



An answer to this question I shall not here attempt though, 

 perhaps, it might be less difficult to find than a reply to the very 

 old question, ''Which was first, the egg or the hen ?" 



V. With regard to the coloration of eggs. Eggs vary even 

 more in their ground colour and markings than in their form, 

 those of the same species, and even of the same individuals, often 

 differing singularly from each other. Those from the same nest 

 even are found at times to differ so considerably, both as to 

 ground colour and markings, that any one, ignorant of the occur- 

 rence of such difference, examining them for the first time apart 

 from the nest, would hardly believe them to have been laid by 

 the same bird. Eor instance, very pale or even perfectly wliite 

 eggs frequently occur, as may be seen in Mr. Jolm Hancock's 

 instructive collection, which have been laid in the nests of birds 

 that produce, normally, highly coloured eggs. 



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