310 PROFESSOR OWEN ON THE GENUS DINORNIS. 



were smooth, low, not rising higher than the cerebellum, hut convex and expanded an- 

 teriorly : the proportion of the cavity to its great posterior outlet indicates the brain to 

 have been smaller in proportion to the spinal chord than in any Struthious or other 

 existing bird. There is no bony falx : the vertical ridge on the fore-part of the ' os 

 petrosum,' for the attachment of the tentorium, is less produced than in the Apteryx : 

 there are no horizontal ridges of bone continued forwards from the os petrosum to define 

 the fore and upper part of a fossa for the optic lobe on each side, as in the Ostrich and 

 most other birds. 



The depressions on the occiput for the insertion of the nuchal muscles indicate the 

 force with which they must have habitually operated upon the head ; and the unusual 

 size and depth of the temporal fossae equally indicate the great strength of tlje gripe of 

 the bill : such a combination of powerful muscles of the head and the beak accords with 

 the indications which the vertebrte of the neck and the short and strong metatarsi afford, 

 of habits of scratching and uprooting vegetables for food. 



Compared with the Ostrich, the occipital condyle is smaller in the Dinornis in pro- 

 portion to the great foramen : the cranium of the Ostrich is narrower, loftier and more 

 convex posteriorly, and much more contracted anteriorly. The form of the cerebral 

 hemispheres must have differed greatly in the two gigantic Struthious birds here com- 

 pared. In the Ostrich the cerebrum is pyramidal, tapering forwards to a point ; in the 

 Dinornis it must have been square-shaped and broadly convex anteriorly. 



Amongst the Grallatorial birds the cranium of the Gigantic Crane {Ciconia Argala) 

 alone equals the present fragment in size, and resembles it in the expanse and degree of 

 convexity of the upper surface ; but it differs, like the Ostrich, in having a more sessile 

 occipital condyle, which is larger in proportion to the foramen : the plane of the foramen 

 inclines in the Argala, as in most other existing birds, from below upwards and back- 

 wards ; and there is a similar inclination in the plane of the supra-occipital surface, 

 ■which more nearly than in the Ostrich equals in breadth that of the Dinornis ; but it is 

 of greater height. The under part of the occipital cond3'le is on a level with that of the 

 basis cranii in the Argala, as in most other birds : in the Dinornis it is raised above 

 that level, or rather the level is carried by the above-mentioned development of the 

 basi-sphenoid below it. The supra-occipital crest is more developed in the Argala, 

 aud the upper part of the skull is indented anterior to it. The temporal fossae are much 

 smaller, and more posterior in position, extending to the occipital ridge in the Argala. 

 The optic foramina are more approximated and the cranial cavity is more contracted 

 anteriorly in the Argala. The articular cavities for the quadrate bones are perforated, 

 zmd more transverse in position in the Argala, as in the Ostrich, than in the Dinornis. 

 The anterior condyloid foramina in both the Argala aad the Ostrich are scarcely half 

 the size of those in the Dinornis, and are situated nearer the condyle. 



The Apteryx has a more hemispheric occipital condyle than the Dinornis, and the 

 plane of the occipital foramen differs in the same degree from that of the Dinornis, in 



