128 PROFESSOR OWEN ON THE GENUS DINORNIS. 
two skulls of corresponding dimensions and characters, one of which is referred by that 
accomplished geologist (and, I believe, rightly) to Dinornis crassus, of which species 
series of limb-bones form part of the same collection, obtained from the swamp at 
Glenmark, which has proved so prolific in evidences of these extinct gigantic birds. 
With this confirmation I proceed to add to the subjoined figures of the skull of 
Dinornis crassus (P\. XI.) notes of the principal differences which it presents in com- 
parison with the skull of D. elephantopus. 
The skull of Dinornis crassus, besides its proportional difference of size, chiefly shown 
in minor length, is distinguished from that of Dinornis elephantopus by a less-convex 
calvarium, relatively narrower and deeper temporal fosse, and above all by shorter and 
terminally broader and more obtusely rounded upper and lower mandibles. 
In breadth of superoccipital surface (Pl. XI. fig. 4, dd) Dinornis crassus almost equals 
D. elephantopus (Pl. X. fig. 2); but it has a sharper, more deeply defined supple- 
mentary upper transverse superoccipital ridge (ib. fig. 2,7), and this is nearer to the 
normal (more or less wavy) upper transyerse ridge (that, viz., which is marked d d in 
fig. 4, and in pl. 38. fig. 38, Vol. III, Dinornis struthiotdes). 
The occipital condyle and foramen (PI. XI. fig. 4, m) differ from those of Dinornis ele- 
phantopus both in size and shape; a larger proportion of the tubercle is truncate above. 
The basioccipital descends more abruptly and relatively lower to the “ platform,” the 
tuberosities forming the hinder angles of which are well produced but more ridged, less 
mammilloid, than in Dinornis elephantopus or D. robustus. 'The sphenoidal platform 
(ib. fig. 3,5) is less deeply impressed, less constricted laterally, by the eustachian 
grooves; and its under surface is flatter, less irregular. The thick paroccipital border 
of the tympanic fossa is subangular, with a superincumbent prominence connecting the 
paroccipital (ib. fig. 1, 4) with the mastoid (ib. 8), rather more marked than in Déinornis 
elephantopus. The mastoid and the premastoid ridge and fossa retain the type of 
D. elephantopus; but the temporal fossa (ib. 7) has less than half the antero-posterior 
breadth, with equal depth: a tract of from 2 to 3 lines intervenes between the super- 
occipital and temporal depressions (ib. fig. 2). The hind part of the postfrontal (ib. 
fig. 1,12) is more deeply excavated by the temporal fossa, and thereby has a sharp 
margin from the origin of the process, that margin being thick and obtusely rounded 
as in Dinornis elephantopus. ‘The antero-inferior boundary-ridge of the temporal fossa 
is continued from the underside, not the hinder part, of the base of the postfrontal. 
There is every sign of the vigorous action of the temporal muscles, although they were 
relatively smaller, and absolutely much smaller, than in Dinornis elephantopus. The 
orbit is not much less than in that larger species. In one skull of Dinornis crassus the 
presphenoid is more carinate than in another. 
The premaxillary (Pl. XI. figs. 1, 2, 3, 22),-with the best-preserved nasal process ( 22’ ), 
gives a total length therealong, in a straight line, of 2 inches 7 lines, the length of the 
process from the point of trifurcation (or the back part of the prenarial septum) being 
