BY H. H. SCOTT AND CLIVE E. LORD. 105 



Thus it will be noted that a transversely oval foramen 

 — and, therefore, one of unequal measxirement — is con- 

 verted into one whose central measurements are equal in 

 both directions. 



If a line is drawn horizontally across the vertex of 

 the skull, it will be found to be exactly five inches above 

 the upper wall of the magnum foramen. 



The par-occipital processes have thickened borders, 

 a,re concave as they contribute moieties to the otocrane' — 

 they are notched for the passage of the nervus vagii. 

 Mesiad — they are confluent with the basi-occipital, and 

 basi-sphenoidal plates of the otocrane. A ridge marks the 

 occipito-sphenoidal suture, but the spheno- sphenoidal 

 suture is overlapped by the enormously extended vomer. 

 The whole of the vertex of the skull is rough and granu- 

 lated, even at times raised into bony callosities, and the 

 sutures proper to this region stand out as ossified ridges. 

 The line of the super-occir)ital — as viewed in profilei — is 

 that of an "ogee," hollow above the magnum foramen, and 

 rounded higher up. A line vertical to the basis crani, 

 and made to touch the occipital condyles, would stand 

 away from the deepest part of the curve of the ogee, an 

 inch and three-quarters. 



The temporal fossae are largely composed of the parie- 

 tals, which are ridged above, and continued posteriorly as 

 two wings that extend a quarter of an inch beyond the 

 line of the super-occipital. These ridges slope backward 

 and downward, finally losing themselves at the exoccipito- 

 squamosal sutures, having upon all their faces, made open 

 parabolic curves. In macerated skulls these curves axe 

 very symmetrical, but in old beach-worn specimens they 

 always suffer much mutilation. The pre-maxillaries ex- 

 pand over the maxillaries at their upper ends, and form 

 two hollow grooves. The maxillaries cover the whole of 

 the frontals, except a wedge-shaped strip on either side of 

 the skull, the bases of these wedges being turned towards 

 the "blowers." In point of size, the frontal strip thus 

 exposed does not exceed one and a half inches, but may 

 vary considerably within this limit in individual skulls. 

 When a line is drawn — mesiad — from the tio of the skull 

 beak to the vertex, the upper edges of the maxillary wings 

 subtend angles of 78 degrees to it. Over the zygomatic 

 arches, the maxillary wings are much thickened — in male 

 skulls of this genus — as much so relativelv as in 

 Glohicephahis and Orca, but female skulls show very little 

 super-ossificatioin in this region. As far as our knowledge 

 goes, no female Tursiops skull ever shelves here, as obtains 

 in Belphinus. It is simply a matter of less super-ossifi- 



