524 STRUCTURE AND CLASSIFICATION OF BIRDS 



been within so limited an area at least twenty-five distinct 

 species is explained by Captain Hutton by the view that at 

 one time the two islands of New Zealand were divided up into 

 a greater number — an archipelago, in fact — the result of this 

 being what we now see among the cassowaries, where each 

 of the islands inhabited by them has its own peculiar species,, 

 isolation, indeed, permitting of the specialisation. All the 

 moas, however, became extinct at a period not less than 

 three or four hundred years ago. T. J. Parker,' whose 

 work on the cranial osteology of the group is the most 

 recent, allows the genera Dinornis, Pachyornis, Mesopteryx, 

 Anomalopteryx, Emeus, and probably Megalapteryx, dis- 

 tributed among three subfamilies. The moas — a general 

 term applied to all these genera — were birds of fair, often 

 large, size. The smaller species ranged from 2^ to 4 feet in 

 height ; the largest were at least thirteen feet high. 



The skull of the moas had a short and wide beak. The 

 occipital condyle is remarkable on account of its ' more or 

 less pedunculate character,' a circumstance which is of 

 importance in considering the relationship to the moas of 

 the Madagascar Mpyornis (see p. 522). 



The orbit is smaller than in other struthious birds. The 

 nasals are peculiar in that they meet behind above the 

 ethmoid, so that no part of the latter bone appears on the 

 upper surface of the skull. It is only in the adult cassowary 

 among recent struthious birds that the ethmoid is entirely 

 hidden on a superficial view, a state of affairs which is 

 brought about by the development of the crest, and does 

 not exist in the young bird. The palate is like that of the 

 emu and cassowary, but is most like that of Apteryx. 



The nasal bone is furnished with a slender maxillary 

 process, or, as in emus, there is a corresponding bone 

 separately ossified. The lacrymal is firmly ankylosed tO' 

 frontal ; its descending process joins ectethmoid. T. J. 

 Paekee has figured and described a peculiar thin scroll-like 

 bone which appears on a lateral view of the skull and pro- 



' ' On the Cranial Osteology, Classification, and Phylogeny of the Dinorni- 

 thidas,' Tr. Z. S. xiii. p. 373. 



