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PROFESSOR OWEN ON THE GENUS DINORNIS. 
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. LIX. fig. 3, a), adapted to that of the inner condyle of the 
femur, is large, shallow, semioval in shape, with the small end turned forward. The 
ectocondylar surface of the tibia (ib. 6) 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, 7) forms the 
low obtuse angle of the epicnemial ridge; the outer continuation of this ridge forms 
the upper border of the ectocnemial process (/). 
The suprafibular facet (ib. fig. 2, 7) is triangular, rough, almost flat. A smooth tract, 
one inch in extent, divides it from the fibular ridge (mm), which is four inches in extent 
and terminates nearly eight inches below the summit of the epicnemial ridge. 
The procnemial ridge (ib. fig. 1, g) 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 (9') 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, 7), and having a thick, smooth border curving to the shaft below its pointed 
end. ‘The intercnemial surface (ib. fig. 1, /), slightly concave across at its upper part, 
becomes almost flat below. The ectocnemial surface (ib. fig. 2,7) is uniformly and 
more deeply concave across; it is 14 inch in width. 
There are (pneumatic?) foramina (ib. fig. 2, 7,7) behind and below the intercondylar 
surface. 
A low longitudinal ridge bounds internally the posterior flat tract of the upper halt 
of the shaft, and opposite the fibular ridge inclines forward and to the inner side of the 
shaft. The medullarterial orifice (ib. fig. 2, 7) is on the inner side of the fibular ridge, 
one inch above its end. 
As the shaft descends the flatness of its back part gradually becomes convex across, 
and loses the rough reticulate shallow markings indicative of muscular origin. The 
ridge (g') continued from the procnemial process, longitudinally and pretty equally 
bisects a great part of the anterior surface of the shaft, and gives the three-sided 
character to that part of the bone. On the inner and anterior part of the tibia, 
