28G 



DKLPIIINID.E. 



the upper ends of the condyles are 1" '3'" apart. They are low and 

 sessile. 



" The foramen magnum is vertically oval, widest above, and 

 notched at the middle of the upper border ; its length, to the end of 

 the notch, is 2", its breadth 1" 3'" ; the breadth across the broadest 

 parts of both condyles is 2" 9'". 



Fiff. 57. 



Skull of Orca brevirostris. 



" The paroccipital (4), an exogenous growth of the exoccipital, 

 forms the back part of the otocrane, towards which it is sinuous or 

 slightly concave, and terminates below in a thick, rough border : this 

 border is divided by a notch from the otocranial plate of the basi- 

 sphenoid ; and just within the verge of that notch opens the canal 

 for the ' nervus vagus.' 



" The superoccipital (3) rises and expands, as in other Delphinidae, 

 into a broad and lofty convex plate, reaching the vertex and there 

 articulating ^vdth the parietals (7) and intei'jDarietal ( 7*) : a low 

 median ridge divides vertically the upper half of the superoccipital. 

 On the inner surface, 1" 6'" above the foramen magnum, a vertical 

 triangular plate of bone descends into the falx ; it is thickest behind, 

 where its base is grooved transversely by the lateral sinus. 



" The alisphenoids coalesce with the fore part of the lateral border 

 of the basisphenoid, in advance of the otocrane, of which it forms the 

 anterior wall or boundary : the base of the alisphenoid is notched 

 posteriorly (tr) for the thii-d, and anteriorly (m) for the second division 

 of the integument ; it expands as it passes outwards, slightly rising 

 to join the parietal (7) and frontal (11), and to overlap the process of 

 the squamosal continued mesiad from the glenoid cavity. The suture 

 between the interparietal (7*) and superoccipital (3) is obliterated, 

 and that with the parietals is partially so. The suture between the 

 parietal and superoccipital remains at its lower half, showing that a 

 narrow strip of the parietal appears on the external surface of the 



