GIGAKTIC SPECIES OF APTEETGIAJV BIED. 165 



tarso-metatarsus, it is altogether more slender and elegant in form than any of its 

 contemporaries. 



Measurements. 



inches. 



Total length 12"05 



Circumference of shaft in middle .... 2-60 



Breadth of proximal end 2-52 



Breadth of shaft in middle 0-82 



Breadth of distal end 1-65 



Antero-posterior thickness 0-70 



Comparing the articular surface of the proximal end with that ni Apteryx, the out- 

 lines appear to be much alike. The ascending rotular or epicnemial ridge of Megal- 

 apteryx, standing vertically above the articular surface, rises, however, much higher than 

 in Apteryx or in most of the Dinornithidse. This is caused by the deeper excavation 

 of the epicnemial channel than in either of the last-mentioned forms. The ento- 

 condylar surface for the articulation of the inner condyle of the femur has also a 

 greater slope downwards and backwards, the intercondylar eminence being so much 

 more prominent than in Apteryx. This greater slope of that surface also exists in a 

 somewhat minor degree in Apteryx. In the Dinornithidis the ectocnemial process, 

 where it starts backwards from the beginning of the procnemial ridge, has the same or 

 nearly the same breadth to its termination ; but both in Apteryx and Megalapteryx it 

 gradually enlarges, so that its broadest part is at its posterior termination, the space 

 for the attachment of the rotular or extensor tendon being well marked. In Megal- 

 apteryx, as in Apteryx, the intercondylar eminence for the attachment of the crucial 

 ligaments is rather flat, while the ectocondylar surface is more developed in the smaller 

 recent bird. 



Below the suprafibular facet, after a flat space of nearly one inch, the fibular ridge, 

 2'75 inches long, rises well above the shaft of the bone. On the inner side, just 

 below its termination, the medull-arterial orifice is situated about two fifths of the total 

 length of the bone from the proximal end, as in Apteryx ; this orifice in Dinoniis is 

 generally situated a little lower. 



The procnemial ridge, owing to the comparatively small breadth of the proximal 

 end and the narrowness of the shaft, is much straighter than in the Dinornithidae, so 

 that there is scarcely any inward inclination, except where it forms the inner boundary 

 of the extensor groove. In fact, it is almost as straight as that of Apteryx, where it 

 forms rather a sharp edge, separating the flat anterior from the rounded posterior surface 

 of the shaft. The so-called pneumatic foramina behind and below the intercondylar 

 surface also exist in Megalapteryx, but they are narrower than in the species of 



