PROFESSOR OWEN ON THE GENUS DINORNIS. 3 



I have applied to the principal elements the names of ' entometatarse ' (ii), ' raesometa- 

 tarse ' (in), and ' ectometatarse ' (iv) respectively, for the convenience of description. 



The shaft in Palapteryx robustus is subtriedral in its upper two-thirds, subcompressed 

 from before backwards in its lower third, of equal breadth in its middle fourth, and 

 thence expands to both extremities, but more to the inner than the outer side, and in 

 a greater degree at the lower end ; so that the inner margin is more concave than the 

 outer one. This difference is not so great in the Dinornis giganteus, in which, also, 

 the shaft continues gradually to diminish in breadth towards its lower third. 



The proximal articular surface of the metatarse of the Palapteryx robustus is divided, 

 as usual, into two concavities, that for the inner condyle of the tibia being the largest 

 and deepest : it is of a triangular form bounded internally by a well-defined edge which 

 extends in a nearly straight hne from the anterior internal angle to the posterior angle 

 of the concavity : the anterior external angle is formed by the prominent fore part of 

 the intercondyloid protuberance. The more shallow concavity for the outer condyle is 

 subcircular, its outer boundary being convex and most raised at its middle part ; pos- 

 teriorly the border subsides and the concavity passes into a convexity at that part. The 

 non-articular surface of the proximal end is chiefly behind the concavities and extends 

 upon the upper part of the calcaneal processes : these are, as usual, three in number, 

 the internal and middle ones being most prominent: they are obtusely rounded, and 

 separated by the deep and wide groove for the flexor tendons of the toes : the lon- 

 gitudinal extent of the inner process (the entocalcaneal one, fig. 2, c e) measures one 

 inch and a half: its obtuse and thick upper end commences behind and half an inch 

 below the posterior border of the entocondyloid cavity : the process gradually contracts 

 to a point at its lower end, which overhangs the smooth groove continued obliquely 

 downwards and outwards to the foramen formed by the persistent remnant of the inter- 

 osseous space between the inner (ii) and middle (in) metatarsal elements of the com- 

 pound metatarse. 



The mesocalcaneal process (fig. 2, c m) is the largest of the three : it is broad and 

 rounded about, shghtly grooved down its posterior surface, and supported by the rough 

 posteriorly projecting buttress-like part of the mesometatarse, of which it seems to form 

 the obtuse summit. 



The ectocalcaneal process is the smallest : it is separated by a shallow open groove 

 from the mesocalcaneal process : it begins to project half an inch below the posterior 

 convexity of the ectocondyloid surface : its lower part subsides before it reaches the 

 foramen between the ecto- and meso-metatarse. The interval between the two inter- 

 osseous foramina, which gives the breadth of the mesometatarse at that point, is greater 

 in the Palapteryx robustus than in the Dinornis giganteus, notwithstanding the greater 

 length of the bone in the latter species. 



The anterior intercondyloid protuberance sends a short obtuse ridge downwards and 

 slightly outwards upon the fore part of the upper end of the tarso-metatarse. A large 



b2 



