1S93.] OSTEOLOGY ETC. OE TUE DINOENITHIU^. 171 



examination of numerous immature specimens the ossification 

 has been determined, and outline figures are giAen showing the 

 boundaries of all the bones and their sliare in the various ridges, 

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

 importance. 



Next follows a detailed comparison of the skulls of the Moas 

 with those of the other Eatitse, this section ending 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 Binornithidce and in the other genera of Eatitse. Care is taken 

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

 measurements are made. A second table gives the 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 BmornitJndce into geuera. He finds 

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

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

 Binornis, Pachijornis, Mesopterij.v, Anomalopterii.r, and Emeus'^. 

 Moreover, PacJuiomis, Mesupten/.c, aud Aiwmalvpteri/.vavii found to 

 present many points of resemblance with one another, of which the 

 most obvious is the narrow, pointed beak. The two broad-beaked 

 genera Binornis and Enu-us, on the other baud, differ strikingly both 

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

 cranial characters only, the Binondtludo: may therefore be divided 

 into three subfamilies as follows : — 



Subfamily «. DinornithinvE. 

 Genus Binornis. 



Subfamily h. Anomaloptebygin.e. 



Genera Pachyornu, Mesojjtcrij.v, and Anomalopte)'t/d\ 



Subfamily c. Emetn^. 

 Genus Emeus. 



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

 characters of the subfamilies and genera. 



Lastly, the phylogeny of the group is discussed. Mesopteryx is 

 considered to be the most generalized form, while Binornis and 

 Emeus are both highly specialized but in opposite directions. Of 

 the other Eatitse, Apieryx comes nearest to the Moas in the struc- 

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

 aud Bromceus to the New Zealand genera. Siruthio and lihea, on 

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

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



' Ko account is taken of Mryalaplenjx, which is included by Lydekker 

 among the BinoriiitkidcB, as nothing is at present known of its skull. 



