4 TEETIAEY VEETEBEATA OE THE EATtTM. 



form of the skull is well shown, other notable points being the highly arched palate 

 and the large median anterior palatine foramen. 



The exoccipitals {exo.) seem to form the whole of the great occipital condyles, 

 though the sutures between them and the basioccipital are obscure. The condyles 

 (text-fig. 1, cond.) themselves are somewhat pedunculate and project entirely beyond 

 any other portion of the skull. Their inner faces are flattened, with a deep depression 

 near their base. The articular surface is much less convex from side to side than 

 from above downwards, in which direction the curvature of the surface is nearly 

 a semicircle. In fact, the articulation may almost be described as a slightly oblique 

 section of a cylinder, and must have allowed great freedom of movement to the 

 head in an up-and-down direction. There is no condylar foramen, or at least 

 none has yet been observed. The foramen magnum (text-fig. 1, f.m.) is large and 

 oval in outline. Its concave upper border is formed entirely by the exoccipitals, 

 which meet in a median suture, thus excluding the supraoccipital entirely from 

 the opening (PI. III. fig. 2) ; while its ventral border, which is nearly straight 

 and somewhat posterior to the upper border, is probably formed mainly by the 

 basioccipital. The suture between the exoccipitals and the supraoccipital runs 

 outwards and somewhat upwards from the middle line (PI. III. fig. 2), and crosses 

 the lower end of the massive lambdoidal crest, of which the thickened and prominent 

 ventral end is therefore formed by the exoccipital. Laterally the exoccipitals are 

 applied by a broad surface to the posterior face of the post-tympanic process 

 (PI. I., PI. II. fig. 1, PI. III. figs. 1, 2k,pty.) of the squamosal, the suture between the 

 two being nearly vertical. Between this squamosal process of the exoccipital and the 

 condyle, below the level of which it projects considerably, there is a blunt prominence, 

 which seems to represent the paroccipital process (PL I., PI. III. fig. l,p.p.). 



The basioccipital (hoc), which, as already mentioned, forms the nearly straight 

 ventral border of the foramen magnum (text-fig. I, f.m.), is broad and flat posteriorly, 

 but its outer boundaries are not clear. Antero-laterally it seems to be notched 

 .on either side by the posterior angles of a pair of large fossse, which open into 

 the cranial cavity, are separated by the narrow anterior portion of the bone, and 

 must in life have lodged the tympanic bones. The anterior portion just mentioned 

 deepens considerably from before backwards, so that near its junction with the 

 basisphenoid the vertical diameter is much greater than the transverse extent. In 

 this anterior region the ventral surface bears a median keel, while a transverse 

 ridge marks its junction with the basisphenoid (PI. II. fig. I, bsp.), the ventral 

 surface of which is likewise keeled in the middle line. The axis of this bone is 

 not quite in the same straight line as that of the basioccipital, but turns slightly 

 upwards in front, its anterior portion being embraced by the upper edges of the 

 pterygoids posteriorly and of the palatines anteriorly. The vomer has not been 

 observed in any specimen. 



