PROFESSOR OWEN ON THE GENUS DINORNIS. 351 



by a median supraoccipital foramen and by two lateral holes. The supraoccipital of 

 Dinornis{3) inclines forwards at an angle of 43° to the horizontal line of the basis cranii 

 (fig. 1,3); it is imperforate above the great foramen. The occipital surface is defined 

 from the upper or parietal surface by a well-marked ridge which describes two strong 

 curves, convex forwards (3, 3, fig. 2), bounded by a thick tuberosity (<) externally, from 

 which the ridge is continued downwards and outwards, describing another forward 

 convex curve (4, fig. 2), to the obtuse paroccipital angle. The whole occipital region is 

 thus bounded above by a festooned arched ridge, formed by the sudden subsidence of 

 that surface below the level of the upper surface of the cranium ; the four festoons or 

 curves being equal and divided by the supraoccipital convexity at the middle, by the ex- 

 occipital tuberosities {t, t) at the sides, and by the paroccipital angles (4) below. The 

 depressions upon the surface so defined, together with the extraordinary extent of the 

 concave posterior surface at the sides and below the occipital tubercle (fig. 4), indicate the 

 mass of the muscles implanted into the back part of the skull, and the strength which 

 must have been exerted to overcome the resistance, to which the nature of the food 

 necessitated the application of the beak. The sides of the basisphenoid which form 

 the base of the tympanic cavity extend outwards in the form of a rugged protuberance 

 (y, fig. 4) which almost meets the tympanic process (s") of the mastoid and grasps the 

 upper and hinder condyle of the tympanic bone (28. fig. 3). 



The alisphenoid which extends upwards and outwards from its anchylosis with 

 the fore-part of the protuberance (y), is perforated or deeply notched by the foramen 

 ovale {tr) immediately anterior to the inner glenoid cavity for the tympanic : its inner 

 surface is impressed by the optic lobes (/, fig. 7) : its outer surface is roughened by 

 muscular attachments ; and, as it bends upwards anterior to the mastoid, into the 

 temporal fossa, its limits are obliterated by anchylosis with the mastoid, parietal and 

 postfrontal which combine to form that fossa. 



The sutures of the parietals, as of the other bones forming the cranial cavity, are ob- 

 literated ; but a very remarkable transverse linear indentation, deepest on each side the 

 middle line (see fig. 2), may, perhaps, indicate the place of the ' coronal ' suture and the 

 anterior limits of the parietals (7) : it is, however, behind the relative position of the 

 persistent coronal suture in the skull of the Palapteryx figured in pi. 39. fig. 5, and is 

 nearer the supraoccipital ridge. There is a median rising where the sagittal suture 

 originally ran ; but the cranium of the Dodo shows a depression and minute foramen 

 at this part. The temporal fossa is wider than in the Dodo : it is bounded above by a 

 sharp ridge, well-defined by the sinking of the surface for the muscular attachment 

 below the smooth level of the upper surface of the parietal and frontal (see fig. 1), and 

 curving from the exoccipital tuberosity (<) forwards and downwards upon the long 

 postfrontal (12). The major part of the temporal fossa is formed by the mastoid' (s) 



' For the facts and arguments proving 8' to be a process of the ' mastoid ' and not of tlie ' squamosal ' (/em- 

 poral, Cuv.), see my worli ' On the Archetype and Homologies of the Vertebrate Skeleton,' 8vo, pp. 32-35. 



