PEOFESSOE OWEN ON THE GENUS DINOENIS. 173 



power of flight, that the sternum does not increase in size in the ratio of the increase of 

 the legs and general stature of the species of Dinornis. 



The length of the present sternum at its mid line, and the breadth from tip to tip of 

 the lateral processes, are less than that of the subject of plate vii. vol. vii. Zool. 

 Trans. But the length of the body of the sternum anterior to the lateral hind notches 

 is greater iu the present bone, whilst that of the part prolonged between those notches 

 is less ; the costal border (Plate XXXII. figs. 3 & 4) is nevertheless absolutely longer 

 in the present sternum ; and although in the angle of divergence of the lateral processes 

 {h. h) it conforms to the type of the sternum oi Dinornis elephantopus, and with it departs 

 iu a marked degree from that of Dinornis rkeides, yet the differences noted are sufficient 

 to indicate that the present perfect sternum accords more closely with that of the 

 skeleton of Dinornis robustus, and has, at least, belonged to a distinct species of the 

 group of Moas, which, on sternal characters, might be denoted by the generic term 

 Palapteryx. 



There is, however, a gradational approach to the less divergent type of sternum 

 exemplified in Dinornis rhe'ides. In {Palapteryx) elephantopus, e. g., the breadth of the 

 fore border of the sternum being 8 inches, that of the bone at the ends of the divergent 

 processes is 15 inches. 



In Dinornis roiustus the breadth of the fore border being 8 inches 3 lines, that of 

 the bone at the ends of the divergent process is 13 inches. 



In Dinornis maximus the breadth of the fore border of the sternum being: 9 inches, 

 that of the bone at the end of the divergent processes is but 12 inches ; moreover, the 

 length of the sternum anterior to the notches is relatively rather more than in D. ro- 

 bustus, and makes a corresponding approach to the more elongate type of sternum, 

 represented by D. rhe'ides. 



With these approaches, in sternal gradations, to that type the limb-bones coincide, 

 showing longer and more slender proportions as compared with Dinornis elephantopus 

 and D. crassus ; so that, even accepting, or resuming for convenience' sake, my old 

 subdivision of Moas into two subgenera, I cannot shut out the conviction of its essential 

 artificiality. 



It is hardly probable that a nominal generic distinction will be ultimately accepted 

 on the difi'erences here pointed out between the sternums of the species of Dinornis 

 outlined in cut, fig. 35, especially as they are associated with corresponding gradational 

 difi'erences of proportion in the bones of the hind limbs. 



Admitting such generic or subgeneric group for the species crassus and elephantopus, 

 showing the extreme divergence of sternal processes with robustness of hind limbs, 

 and if the term Palapteryx had not had priority, I must have adopted Eeichenbach's 

 Emeus'^, of which my Dinornis {Palapteryx) crassus is the type. 



' Das uatiirliche System der Vogel, 4to, 1849-50, p. xxx. 



• 2b2 



