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Rh the Apteryx, which in the case of that of A. mantelli, as laid in the Zoological Gardens, weighed 14½ oz., while the contents were 13½ oz., and the living female herself 60 oz., her egg being nearly one fourth the weight of the parent.

In 'The Ibis' (3rd ser. vol. iv. July 1874, p. 215), Dr. J. Haast, in his article on the extinct birds of New Zealand, makes mention that "Of Meionornis casuarinus [rectius Mionornis] we have a series of four clearly defined sizes in our possession." The same variation is spoken of in other fossil species. He goes on to observe, "If we compare two skeletons of Apteryx australis, male and female, and two of A. owenii, male and female, wdth each other, a similar distinct gradation is observable."

In their memoir on the Solitaire, the Didine bird of Rodriguez, Pezophaps solitaria (Gmel.), Professor Newton and his brother Mr. Edward Newton express themselves "much embarrassed by the wealth of their materials."

They allude to the extraordinary variation in size. This variation had previously deceived even such experienced persons as Strickland and Mr. Bartlett, and it extended to "the relative proportion of divers parts of the bones." I have observed in various living birds of the same species, for many years past, an extraordinary variation in size. But this subject is too long.

The defenceless condition of these birds, deprived of any volant power, renders it necessary that the newly hatched young, like all those called by Professor Owen "Aves prsecoces," should run about and provide food for themselves as soon as they leave the shell. At p. 257, vol. ii. of his 'Anatomy of Vertebrates,' he gives the number of davs of incubation in thirty-two species of different orders; they vary from the Wren (Troglodytes vulgaris), which sits ten days, to the Emu (Dromaius novæ-hollandiæ), which takes fiftyfour. Dr. Buller mentions a female Apteryx in his aviary which for forty days before extrusion of her egg moved with difficulty; and though the exact time cannot be given, yet it is certain that it is unusually long, perhaps as much so as in any known species.