STEXEOSAUBUS. 89 



lateral temporal fossa it unites above with the postfrontal for a short distance ; in 

 front of this it widens further and forms the lower border of the orbit, in front of 

 which again it unites for some distance with the lower edge of the lachrymal, 

 terminating forwards in a point. The ventral edge of the anterior portion of the jugal 

 unites with the maxilla in front and with the trauspalatine posteriorly. 



The occipital surface (PI. V. fig. 3) shows well the great compression of the skull 

 from above downwards, its width being much greater than its height. The supra- 

 occipital (s.oc.) is a small bone completely shut off from the foramen magnum (f.m.); 

 it unites with the exoccipitals below in a convex suture, and with the parietals 

 above in a nearly straight one. Along its junction with the parietals there are two 

 depressions separated by a slight median vertical ridge which extends up on to the 

 parietals ; it is probable that a foramen opens into each of the depressions. The 

 exoccipitals (ex.o.) are large bones which meet in the median line above the foramen 

 magnum in a vertical suture, and thus, as already noticed, completely exclude the 

 supraoccipital from that opening. They form a great part of the occipital surface of 

 the skull, being produced outwards into large paroccipital wings. At their lower end 

 they unite with the basioccipital, and take a very small share in the formation of the 

 occipital condyle ; beneath this they unite with the outer sides of the ventro-lateral 

 processes of the basioccipital (boc.) and thus form the outer portion of those 

 prominences. External to this the border turns sharply outwards, passing into the 

 lower edge of the paroccipital process ; at the angle thus formed there is a large 

 foramen which transmitted the carotid artery {car.), and perhaps also the vagus group 

 of nerves. The lateral wing of the exoccipital is very large ; it consists of a lower 

 portion, convex from above downwards and closely united with the upper surface of the 

 quadrate, and an upper (paroccipital) portion which forms a strong overhanging ledge 

 separated from the lower part by a groove which deepens greatly from within outwards, 

 so that at its outer end the exoccipital is deeply notched into an upper and a lower 

 division. The anterior face of the upper portion unites closely with the upper ramus 

 of the squamosal and with it forms the posterior wall of the supratemporal fossa. 



The basioccipital (boc.) forms the whole of the occipital condyle, with the exception 

 of the small portions of the upper outer sides borne by the exoccipitals. The upper 

 border between the bases of the exoccipitals is flattened or gently concave, but the 

 remainder of the condyle is nearly evenly convex, the transverse diameter being 

 a little greater than the vertical one ; about the middle of the convexity there is a 

 slight dimple. Ventrally the condyle is sharply marked off from the rest of the bone 

 by a strong transverse groove, forming a kind of short neck. Ventro-laterallv it 

 bears a pair of large tuberosities, directed outwards and downwards and projecting 

 most prominently at their posterior angle ; the hinder part of the outer face of these 

 projections is overlapped by and unites closely with processes of the exoccipitals ; 

 ventrally they are separated by a deep fossa, narrowing and deepening forwards to an 



PART II. n 



