124 PROFESSOR OWEN ON THE GENUS DINORNIS. 
halfway down towards the foramen magnum. The paroccipital ridge takes the same 
course, but is not bent backward as in D. robustus; its lower angle (ib. fig. 2,4) is 
divided by a notch from the carotid fossa. The paroccipital process is more con- 
tracted toward its lower end. The basisphenoid resembles in shape that in D. robustus, 
but the pterapophyses! (ib. fig. 4, 5’) are relatively shorter ; the oblique eustachian 
grooves (ib. e) are well marked. ‘There is a median venous foramen, in two skulls, 
between the origins of the pterapophyses, in one skull accompanied by a groove 
(ib. fig. 4,5). 
The crenate transverse occipital ridge, answering to that marked d d, pl. 38. fig. 3, 
vol. iii. (Trans. Zool. Soc.), instead of two, shows three curves on each side of the median 
vertical ridge (Pl. X. fig. 2,3), answering to as many insertions of nuchal muscles. In 
advance of this ridge, upon the upper surface of the cranium (Pl. X. fig. 3), is a second 
transverse ridge (ib. 7), not parallel with the former, but with a greater bend convex 
forward; it is formed in the same way, viz. by the rise of the outer surface in advance 
of the depression for muscular insertion. his second ridge is from 4 to 7 or 8 lines 
in advance of the first; it seems to correspond with the place of the lambdoidal suture 
in the young bird, here and in other adult skulls quite obliterated. 
The mastoid process (fig. 1, 8) is as long as in Dinornis robustus. The premastoid 
(ib. 8’) is a ridge produced into a short point; the intervening concavity gives attach- 
ment to the postcrotaphyte fascicule or muscle. A longitudinal ridge extends from 
above the base of the mastoid, backward, overhanging somewhat the tympanic fossa, 
and joining the outer margin of the paroccipital at a right angle; to a ridge within this 
border, part of the ear-drum was attached, and the ridge, before it subsides, indicates 
the ecto- and entotympanic surfaces of the paroccipital (ib. 4). ‘The tympanic cavity is 
formed as described in D. robustus, as is also the articular cavity for the tympanic bone. 
The characters of the “ foramen ovale” and “ prelacerate fissure,” with its divisions into 
the optic foramen and those for the fourth nerve, the anterior division of the fifth, and 
the sixth nerve, are as in D. robustus. The right and left optic foramina are 7 lines 
apart; at the intervening space are the deep fosse impressing the upper part of the sides 
of the beginning of the presphenoid (fig. 4,9) and confluent orbitosphenoids (ib. 10). 
The temporal fosse are well defined, are similar in shape to and quite as large as 
those in Dinornis robustus: the least interspace between their upper ridges is 2 inches ; 
but this varies a little in different specimens. ‘The posterior division of the temporal 
fossa (Pl. X. fig. 1, 8 8’) is smaller relatively to the anterior division (ib. 7) and to the 
entire cranium than in D. robustus. 
On the upper part of the cranium (PI. X. fig. 3) a rough surface extends forward from 
the upper normal transverse occipital ridge for about half an inch at the mid line; it is 
1 Trans. Zool, Soc. vol. iii. p. 351 (January 1848), and Osteol. Catal. Mus. Coll. of Surgeons, p. 303, no 1601: 
my “ pterapophysis” is the “ éminence particuli¢re qui provient du sphénoide” of the Legons d’Anat. Comp., 
ed. 1835, tom. iv. prem. partie, p. 111. 
