62 PROFESSOR OWEN ON THE GENUS DINORNIS. 



The chief difference which the skull under consideration presents as compared with 

 that figured in pi. 54, vol. iii., is the greater relative extent of the osseous body of the 

 premaxillary, and of its downward curvature, in which it resembles in the same degree 

 the skull presumed to be of the Dinornis figured in pi. 52, vol. iii. 



From the remarkable modifications of the back part of the cranial portion of that 

 skull, its generic distinction from the large skull under consideration is evident ; and 

 if we refer the present large cranium to the genus Dinornis, distinguished as it is by its 

 superior extent and curvature of the bony beak from the skull referred to Palapteryx, 

 then the still more remarkable skull figured in pi. 52 might possibly belong to the 

 genus Aptornis, of which the equally remarkable bones of the legs have been described 

 and figured in a preceding Memoir'. It seems, however, to be too large for those 

 small metatarsi. 



The skull of, perhaps, a larger species than the subject of the previous description, is 

 indicated by the hinder half of the cranium (PI. XXIV. figs. 1, 2 & 3), which, by the 

 persistency of the sutures, the absence of the superoccipital and temporal ridges, and 

 the smooth exterior of the bones, has belonged to a young individual of, it may be, the 

 Dinornis giganteus. The occipital condyle {ib. fig. 2, i ) is larger than in the older skull ; 

 the elements of the occipital bone have coalesced : but the lambdoidal suture dividing 

 the superoccipital (s) from the parietals (7), the sagittal suture (s), and that dividing the 

 parietals (7) from the mastoids (a), and both these from the ahsphenoids, remain. Not 

 any of these sutures are dentated ; they are more properly ' harmonise': the sagittal is 

 the most irregular or wavy. The particular form of the cranial bones of the Dinornis is 

 indicated by these sutures. 



The superoccipital (3), as in the skull last described, deviates most, by its great breadth 

 and small height, from that in other birds : the middle and major part of its anterior 

 margin is slightly convex, or subangular forwards, the outer parts notched for the recep- 

 tion of the posterior external angles of the parietals : yet, notwithstanding the Uttle 

 elevation of the superoccipitals, it reaches the level of the upper surface of the cranium, 

 owing to the flatness of the parietals : it slopes forwards at once from the upper border 

 of the foramen magnum. The broad paroccipitals (4 ) spread outwards and backwards, 

 and nearly attain the level of the upper surface of the cranium. 



Each parietal terminates behind in an obtuse angle, which penetrates a corresponding 

 emargination in the superoccipital near its outer angle ; and it sends a rounded pro- 

 jection from its anterior border, near its outer angle, which enters a corresponding 

 emargination between the frontal and postfrontal. The outer part of the parietal 

 bends down, forms the bottom of the temporal fossa, and meets the alisphenoid near 

 the lower part of that fossa at a straight longitudinal suture. The tumid mastoid (s) 

 forms the outer and posterior angle of the upper surface of the skull, as in the Crocodile, 

 and is wedged between the parietal, superoccipital, alisphenoid, and tympanic bones, 



' Zool. Trans, vol. iv. p. 11. pi. 3. figs. S-S. 



