1893.] OSTEOLOGY ETC. OE THE BIXORNITIIID.E. 171 



examiuatioii of numerous immature specimens the ossification 

 has been determined, and outline figures are gi\en showing the 

 boundaries of all the bones and their share iu the various ridges, 

 processes &c., the special characters of which are of classilicatory 

 importance. 



Xext follows a detailed comparison of the skulls of the Moas 

 w ith those of the other Eatita?, this section enduig with a summary 

 of cranial characters in the whole subclass. 



A table of measurements is then given showing the chief dimen- 

 sions, in millimetres, of the skull in the more important species 

 of Dinorniihidce and in the other genera of Eatita?. Care is taken 

 to define as exactly as possible the precise way in which the 

 measurements are made. A second table gives tlie leading 

 measurements expressed as percentages of the length of the basis 

 cranii, a series of indices being thus obtained which are frequently 

 of use in the definition of genera and species. 



The author next discusses the bearing of these facts upon the 

 question of the division of the Dlnornithidce into genera, lie finds 

 that — judging from the skull alone and taking no cognizance of 

 the rest of the skeleton — five genera can be distinguished, viz. 

 Dinornis, Pachi/ornis, JSJesopterij.v, Anomalopteriia', and Emtus^. 

 Moreover, Fadii/ornis, Mcsoptcrii.v, and Anomalojdcrifxave found to 

 present many points of resemblance with one another, of \\ hich the 

 most obvious is the narrow, pointed beak. The tv\o broad-beaked 

 genera Dinoniis and Eiiu'ks, on the other hand, differ strikingly both 

 from one another and from the narrow-beaked forms. Iteiying on 

 cranial characters only, the Dlnoraitlikla- may therefore be divided 

 into three subfamilies as follows : — 



Subfamily a. Dinoexithin.e. 

 Genus Dinomis. 



Subfamily h. Axomaloptehygin.e. 



Genera Fachi/onn.'i, MesojjUnj.v, and AnoincdoiJleri/d: 



Subfamily c. Emetn.e. 



Genus Emeus. 



This section of the paper ends with a suuuuary of the cranial 

 characters of the subfamilies and genera. 



Lastly, the phylogeny of the group is discussed. Mesopteri/a' is 

 considered to be the most generalized foi-m, while JJiaoniis and 

 Eiiitus are liotli highly specialized but in opposite directions. Of 

 the other Ratitje, Ajderjjx comes nearest to the Moas in the struc- 

 ture of its skull, and strong alllnities are shown by both Casuarius 

 and Dromcms to the New Zealand genera. Struthio and llhea, on 

 the other hand, show no special afHnilies, as far as the skull is 

 concerned, either to the Australian forms or to one another. 



' Xo accoiiiil is lakeii of Mri/n/a/i/i ,i/.i; wliicli is inchidi-d In Lydckkfr 

 among the Diiuirnithidcp, sis nolliinji is iit [iresent known of its skull. 



