522 PROFESSOR OWEN ON THE 
by the backwardly produced ento- (11) and ecto- (Iv) trochlex, is shallow, but well 
defined. 
The entotrochlea (11) is convex anteriorly, canaliculate behind, and chiefly through 
the production of its inner and hinder part. The ectotrochlea (Iv) is less concave, 
almost flat, transversely, behind, its outer and hinder border being less produced and 
more rounded off. The depression (/*) on the outer side of the ectotrochlea is rather 
deeper and better defined than that on the inner side of the entotrochlea (fig. 4, 11). 
The outer trochlea does not extend so low down as the inner one; and the interspace 
between it and the mid trochlea reaches higher up, especially behind, so that the outer 
part of the neck of the mid trochlea (fig. 2, 111) is the longest. The mid groove of that 
trochlea runs from the fore to the hind part, and is deepest anteriorly (fig. 3, 111). 
As compared with Didus, the entocondylar cavity (a) is deeper, and the margin 
better defined, in Pezophaps (figs. 12,13). The intercondylar tubercle is higher and 
less obtuse in Pezophaps. The hind border of the entocondylar expansion extends 
further in Pezophaps than in Didus before passing to the inner side of the entocalcaneal 
process (ib. 7). The upper border of the entocalcaneal process is thinner in Pezo- 
phaps. The calcaneal canal (¢) is smaller. The tendinal groove (fig. 1, ~) is shallower. 
The ectocalcaneal process (s) is narrower: the groove on the outer side of that process 
is also narrower, and is defined by a ridge not developed in Didus. The short ridge or 
process below the posterior margin of the entocondylar cavity in Dzdus (fig. 10, 7) is 
more developed; it is feebly indicated in Pezophaps, and is continued into the ento- 
gastrocnemial ridge (fig. 4, 7), which is not the case in Didus. Didus has not the 
entometatarsal ridge (fig. 4, ¢) anterior to the entogastrocnemial ridge (ib. g), but only 
the latter, which is strongly marked and more internal in position (fig. 16, 9). 
The postinternal depression (fig. 2, 7) receiving the larger of the two upper inter- 
osseal canals (2) is narrower, and in Pezophaps minor deeper, than in Didus, owing to the 
more posterior position, in Pezophaps, of the entogastrocnemial ridge (gy) defining that 
depression internally. The antero-superior interosseal depression (7) is deeper in Pezo- 
phaps than m Didus; but the insertional surface for the #2bialis anticus (fig. 14, n) is 
better-defined in Didus. The anterior ectometatarsal ridge (fig. 1, 4) is more strongly 
marked in Pezophaps than in Didus. 
The groove leading to the lower interosseal canal is more strongly marked in Didus 
(fig. 15, p) than in Pezophaps (fig. 8, p), and indicates a more powerful “adductor 
muscle,” the tendon of which emerges at the interspace between the neck of the middle 
and outer trochlez, in its course to be inserted into the outer toe. 
The middle trochlea (111), as compared with the outer (Iv) and inner (11) trochlew, is 
larger in Pezophaps (fig. 3) than in Didus (fig. 15); its relative position to the outer and 
inner trochlew, and the consequent curve which they describe transversely, I find, in the 
specimens before me, to be the same in both extinct genera. 
In order to facilitate future comparisons and the following of the above descriptions, 
