376 PROFESSOR OWEN ON THE GENUS DINORNIS. 
On comparing the metatarsus of Aptornis with that of Notornis, Ocydromus, or 
Tribonyx, the bone* would seem, at first sight, to drive the extinct genus far away from 
the Ralline waders: the occiput of 4ptornis hardly presents more marked differences 
from that in any known recent Ralline’s skull. 
I discern, however, a certain harmony in the departures from type thus presented by 
the two extreme parts of the skeleton of Aptornis—an associated relation to the needs 
and habits of this most strange brevipennate bird. On the functional hypothesis of the 
large and long adze-like bill of 4ptornis, as being designed and used for the purpose of 
feeding its great body with earthworms and burrowing grubs, the delving-instrument 
may have needed another one to clear off the broken-up surface and to help in the 
unearthing quest. What, then, we may ask, would be the modifications superinduced, 
say, upon the Ralline type, if indeed such type-characters be not predicable of a wider 
range of the “ precocious birds” ? 
In the first place, the foot, if it is to be used, with due vigour, in scratching up and 
scraping away soil, must be brought near to the bending powers; their force must 
not be wasted upon long tendons traversing a stilt-like metatarsus before they can be 
inserted into the toes. ‘The shortness of that segment in proportion to the tibia is 
accordingly notable in scratchers (Rasores, Gallinw) as compared with waders (Grail). 
The metatarsus is less remarkable for its length in most Rallide than in waders 
generally ; but that of Aptornis is reduced to shorter proportions than have been seen 
in any known grallatorial or, even, rasorial bird. In some of the Grouse-tribe the meta- 
tarsus may be reduced to one-half the length of the tibia; but in A4ptornis it is less 
than half. In strength or robustness it loses nothing in this comparison with Galline, 
rather gains; the transverse diameter of the middle (narrowest part) of the shaft of the 
metatarsus in Aptornis is equal to, or exceeds, that of either the tibia or the femur. 
For the strength of a “double joint,” equality of the two condyles, and of their cups, 
may be a condition, as well as prominence and depth of interlocking; and both ecto- 
and entotibial cups on the proximal articular surface of the metatarsus in Aptornis 
are almost on the same level: the outer one (ectotibial) is rather the lowest; and this 
may be deemed significant of its porphyrian affinity, seeing that the level of this surface 
is conspicuously lower, in Coots, than that of the inner (ento-tibial) cup; and this cup, 
though higher, is deeper than the outer one, as in Rallidew generally. The intervening 
rise of the proximal surface, however, which, as it passes into the joint between the 
condyles of the tibia, is called “intercondylar,”’ instead of being low, as in Rallide, 
is raised considerably ; but this is in more direct relation with the strengthening of the 
ankle-joint than is the equality or level of the two cups and balls. 
The perforate condition of the strongly produced calcaneal process seems, with the 
shortness and thickness of the metatarsus, to speak for the rasorial affinities of the bird 
to which it belongs. But there are no longitudinal grooves upon either the back or 
* Trans. Zool. Soc. yol. iv. pl. 3. figs. 5-8; and Pl. XLIYV. figs. 1-6, of the present Memoir. 
