144 PROFESSOR OWEN ON THE GENUS DINORNIS. 
A small portion of the upper ridge of the great trochanter has been broken off: when 
entire, the femur of the Din. gracilis presents the average length of that of the Din. 
struthioides ; but it is more slender in proportion, the head is smaller, and is supported 
by a better marked constriction or neck, especially at its under part. The upper plat- 
form of the trochanter is narrower, the anterior border of the trochanter not being 
extended so far forwards and outwards. ‘The angle between the upper and fore surfaces 
of the trochanter is a right one, and they meet at a sharp ridge. The rough oval 
surface between the head of the femur and the base of the trochanter is smaller than 
that of the Din. struthioides. The outer irregular surface of the trochanter is of much 
less breadth in the Din. gracilis. The muscular impressions at the sides of the shaft 
meet and form a longitudinal ridge along the back part of the middle third of the shaft : 
they are separated by a tract of half an inch in the Dinornis struthioides, and terminate 
below in two tuberosities. The corresponding ridge formed by the meeting of the vasti- 
muscles along the fore part of the shaft is shorter in Din. gracilis than in Din. stru- 
thioides. 
The most marked distinction, however, is presented by the distal extremity of the 
bone, which is not only relatively less expanded in the Din. gracilis, but the rotular 
groove is narrower, and is bounded laterally by condyloid eminences of more nearly 
equal length; the external one not rising so high up, nor describing the sigmoid curve 
in descending, as in the Din. struthioides. The rotular groove in the Din. gracilis is 
impressed by a transversely oval rough depression, at its upper part, with sharp lateral 
borders, which depression does not appear in any of the femora of the Din. struthioides. 
The popliteal space is triangular and better defined in the Din. gracilis; the fibular 
groove is shorter and less angular, and the rough deep pit above it is smaller. The 
tibial surface on the inner condyle is relatively smaller. 
Tibia. 
The same character is repeated on the proximal end of this bone, where the surface 
applied to the inner condyle is absolutely smaller than in the Din. struthioides, although 
the entire bone, as shown in the subjoined admeasurements, is longer in the Din. gracilis : 
it is also, as the name of the species implies, more slender in proportion to its length. 
This bone (Pl. XLII. fig. 1) was obtained from beneath a sandy deposit, about two 
feet below the surface, at a locality between Wanganui and Turakina, North Island of 
New Zealand, by the Rev. Mr. Taylor. 
Dz, gracilis. 
in. lin. 
The entire length of the boneis . . . . . . 23 6 
The transverse breadth of its proximalend . . 5 O 
The transverse breadth of its distalend . . .- 2 10 
The circumference of the middle of the shaft. . 4 6 
The fibular ridge extends down the shaft 9 6 
