PKOF. H. G. SEELET ON DELPHINOGlfATHirS CONOCEPHALtrS. 471 



centim, high by 1-3 centim. wide. The occipital condyle is inferred 

 from the fracture to have been fully 4 centim. wide. The exoccipital 

 bones as preserved are large and extend outward and slightly 

 upward. On their infero-lateral borders they receive the quadrate 

 bones, which lie internal to and behind the squamosal bones. The 

 quadrate bones extend below the occipital condyle ; their posterior 

 surfaces are flattened, inclined somewhat forward, and vertical when 

 seen from behind. Each quadrate bone terminates in a pedicle, 

 with a vertical condyle which looks forward (fig. 1), is saddle-shaped, 

 4 centim. wide, and relatively shallow, concave transversely and 

 convex from front to back. The transverse width of the interspace 

 between the condyles of the quadrate bones is 6 centimetres. The 

 supra-occipital bone is a sub-quadrate ossification above the foramen 

 magnum, which Kes between the exoccipital bones. The details of 

 these elements of the occipital plate are lost, and its lateral margin 

 is injured by fracture. 



The interparietal bone appears to form the summit of the 

 occipital plate as in Dicynodonts. It is of transversely oblong form, 

 has a squamous union with the supra-occipital, and lies in front of 

 that bone so that it is partly overlapped by it. It shows a slight 

 median vertical ridge. 



The superior surface of the skuU comprises a long, narrow, 

 triangular pre-orbital portion which is badly preserved ; and a re- 

 markably wide sub-pentagonal supra-cerebral region behind, which 

 is defined by the occipital plate behind, and laterally by the borders 

 of the temporal vacuities, and by the orbits. The transverse width 

 of the post-orbital mass is about 11 '5 centim. It rises in the form 

 of a cone to a height of several centimetres above the level of the 

 frontal margin of the orbit, and terminates superiorly in a large 

 circular parietal foramen which is nearly 2 centim. in diameter. 

 The middle of this foramen is situate vertically above the posterior 

 border of the orbit. The external surface of the cone is smooth, 

 and furrowed with vascular impressions which radiate in every 

 direction. If the foramen were fancifully compared to the crater of 

 the cone, these markings would simulate the irregularities of lava- 

 streams. 



This conical crown to the head descends posteriorly and laterally 

 into the temporal vacuities, which are convex from above downward, 

 concave from back to front, and marked with longitudinal ridges. 

 The antero-posterior measurement of the vacuity is 5 centim. ; and 

 the measurement is 11 centim. from the summit of the parietal 

 cone to the superior margin of the squamosal bone, which defines the 

 temporal fossa. That vacuity is limited in front by the post-frontal 

 bone, which forms the posterior border of the orbit. The malar bone 

 may be excluded from the zygoma, which descends as a nearly 

 vertical curved bar extending from the frontal to the squamosal. 



The orbit of the eye is 7 centim. in diameter, nearly circular, 

 vertical, and looks outward and forward. The frontal bone which 

 presumably forms its upper border is thickened, rounded, and marked 

 with small vascular impressions. This inflated superior margin is 



