350 
trochlea, are much alike in the two species ; but the differences above defined impress 
me with the conviction that ornithologists would find the birds to which the metatars1 
of Din. crassus and Din. gravis belonged, if they had them entire to compare, to be 
distinct species. 
The number of the living species of Casuarius which have of late years been dis- 
covered in detached remnants of the great Australasian continent, show much more 
striking differences in plumage and dermal appendages than could have been suspected 
from any differences which are discernible in the bones of the legs ; and these differences, 
when most distinct, are less marked than those above demonstrated in the metatarsals 
of the species of Dinornis which least differ in general size. 
The tibia of Dinornis gravis (Pl. XLII), in comparison with that of Dinornis crassus, 
which it most resembles, has a stronger or thicker shaft in proportion to its length’, 
The character of the metatarsal bone of Dinornis gravis is here repeated, but in a minor 
degree. For the rest, the modifications of the dinornithic character of the tibia which 
the stouter-legged species (D. robustus, D. elephantopus, D. crassus) present are closely 
repeated in the tibia of D. gravis. 
The articular surface (Pl. XLII. fig. 3, a), adapted to that of the imner condyle of the 
femur, is large, shallow, semioval in shape, with the small end turned forward. ‘The 
ectocondylar surface of the tibia (ib. 2) is comparatively small, in the form of a tuber- 
osity, the outer and hinder half of which is applied to the inner side of the ectocondylar 
ridge which divides the tibial from the fibular part of the articular surface at the distal 
expansion of the femur. The intercondylar channel (¢) is wide and shallow, and slightly 
expands as it curves from behind, forward and outward, to the ectocnemial cavity. 
Anteriorly it is bounded by the low, rough, intercondylar eminence (ib. d) for the 
attachment of the crucial ligaments. The epicnemial channel (/) is smooth, broad and 
shallow. 
The rotular or epicnemial ridge (¢) bounds the anterior and outer half of the proximal 
expansion of the tibia. The upper end of the procnemial ridge (ib. fig. 1, g) torms the 
low obtuse angle of the epicnemial ridge; the outer continuation of this ridge forms 
the upper border of the ectocnemial process (h). 
The suprafibular facet (ib. fig. 2, /) is triangular, rough, almost flat. A smooth tract, 
one inch in extent, divides it from the fibular ridge (m), which is four inches in extent 
and terminates nearly eight inches below the summit of the epicnemial ridge. 
The procnemial ridge (ib. fig. 1, ) is continued uninterruptedly down the fore part 
of the shaft with as much inward inclination as makes it, at the lower third of the 
bone, the inner boundary (g') of the “ extensor groove” (ib. p). ‘The ectocnemial process 
or ridge (ib. 4) is much shorter and thicker, subsiding four inches below the summit of 
the epicnemial ridge, but extending outward two inches from the suprafibular facet 
(fig. 2, 2), and having a thick, smooth border curving to the shaft below its pointed 
* See Table of Admeasurements, p, 356. 

