2G PROFESSOR OWEX ON INDIAN CETACEA. 



The elements of the occipital have coalesced. The basioccipital (PI. IX. fig. 3, i ) 

 ionns the lower fifth of the foramen magnum, intervening for an extent, measured in a 

 straight line, of 10^ lines between the lower ends of the occipital condyles (ib. 2') : it is 

 licre thick and concave transversely : it becomes thinner vertically and expanded later- 

 iilly as it advances to join the basisphenoid (ib. s), with which it has coalesced : a slight 

 median longitudinal obtuse rising divides two large shallow concavities, from the sides 

 of which the aliform expansions of the basisphenoid extend, which bend slightly down- 

 ward to form the lower and inner or mesial wall of the otocrane (ib. or). The occipital 

 condyles (figs. 1 «& 3,2,2) are narrow, vertically elongate, oval convexities, wider at 

 their lower half, with the mesial margin gently convex, the lateral or outer margin 

 sinuous, through a slight concavity marking ofi" the upper third of the condyle : the 

 length of the condyle in a straight line is 2" 1'", the greatest breadth 1" 11'" : 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 last notch, is 2", its breadth 1" 3'" ; the breadth 

 across the broadest parts of both condyles is 2" 9'". The paroccipital (figs. 1 & 3, 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, 

 4'" across the thickest part (figs. 3, ■!"'); this border is divided by a notch from the 

 otocranial plate (s') of the basisphenoid, and just within the bottom of that notch' 

 opens the canal for the nervus vagus. The superoccipital (figs. 1, 2, 3) rises and ex- 

 pands, as in other Ddpldnida', into a broad and lofty convex plate reaching the vertex, 

 and there articulating with the parietals (?) and interparietal ( '* ) ; a low median 

 ridge (fig. 2, 3' ) 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 (PI. IX. figs. 1, 3,6) coalesce with the fore part of the lateral borders 

 of the basisphenoid, in advance of the otocrane (fig. 3, o?'), of which it forms the anterior 

 wall or boundary : the base of the alisphenoid is notched posteriorly for the third, and 

 anteriorly for the second, division of the trigeminal ; it expands as it passes outward, 

 slightly rising (fig. 1, c)to join the parietal (7), and frontal (n), and to overlap the 

 process of the squamosal (fig. 3, iv ), continued, mesiad, from the glenoid cavity (a). The 

 suture between the interparietal (fig. 2, ?*) 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 (fig. 1, ? ), showing that a narrow strip of the parietal appears 

 on the external surface of the cranium, extending backward, between the squamosal 

 (2/) and superoccipital (s) to the exoccipital (2), and slightly expanding at its junction 

 therewith. 



The presphenoid (ib. fig. 3,9) is distinct from the basisphenoid (s), and extends in 

 the form of a compressed rostrum forward, contracting, to be enclosed by the pos- 

 terior sheatli-sliapod part of the vomer ( is ). The orbitosphenoids (ibid. 10) extend 



