PEOFESSOE OWEN ON THE GENUS DINOENIS. 365 



degree. For the rest, the modifications of the dinornithic character of the tibia which 

 the stouter-legged species {D. robustus, D. elephantojius, B. crassus) present, are closely 

 repeated in the tibia of I), gravis. 



The articular surface (PI. 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. b) 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 (c) is wide and shallow, and slightly 

 expands as it curves from behind, forwai-d 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 [f) is smooth, broad and 

 shallow. 



The rotular or epicnemial ridge {e) bounds the anterior and outer half of the proximal 

 expansion of the tibia. The upper end of the procnemial ridge (ib. fig. 1, g) forms 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, I) 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, 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 {g') of the " extensor groove" (ib. ])). The ectocnemial process 

 or ridge (ib. h) 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, I), and having a thick, smooth border cui-ving to the shaft below its pointed 

 end. The intercnemial surface (ib. fig. 1, k), slightly concave across at its upper part, 

 becomes almost flat below. The ectocnemial surface (ib. fig. 2, i) is uniformly and 

 more deeply concave across ; it is 1 1^ inch in width. 



There are (pneumatic'?) foramina (ib. fig. 2,j,j) behind and below the intercondylar 

 sui-face. 



A low longitudinal ridge bounds intei-nally the posterior flat tract of the upper half 

 of the shaft, and opposite the fibular ridge inclines forward and to the inner side of the 

 shaft. The meduUarterial orifice (ib. fig. 2, n) is on the inner side of the fibular ridge, 

 one inch above its end. 



As the shaft descends the flatness of its back pai't 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, 



