7. ORCA. 287 



cranium, extending back-ward, between the squamosal (27') and super- 

 occipital (3) to the exoccipital (2), and slightly expanding at its 

 junction therewith. 



" The presphenoid is distinct from the basisphenoid, and extends 

 in the form of a compressed rostrum forward, contracting, to be 

 enclosed by the posterior sheath-shaped part of the vomer. The 

 orbitosphenoids extend outward, overlapping the pterygoids, contract 

 where they form the fore part of the foramen laccrum anterius and 

 the optic foramina, beyond which they expand to support the orbital 

 plate of the frontal. 



"The frontals(ll,ir), in great part overlapped, as in other Cetacea, 

 by the maxillaries (21), show, at their narrow exposed strip, extending 

 transversely across the summit of the cranium, the persistent frontal 

 suture, half an inch in length: from this suture, the strip curves 

 outward and backward, expanding beyond the interparietal (7*), 

 and then downward and forward, contracting, and again expanding 

 to form the postorbital process (12), which is triangular and three- 

 sided, one facet being a continuation of the exposed strip, a second 

 contributing to the temporal fossa (t), and a third to the orbit (or). 



" In the temporal fossa (t) the frontal (11) articulates with the 

 parietal (7) and alisphenoid ((>), in the orbit with the orbitosphenoid 

 and malar ; then arching forward from the postorbital process, the 

 frontal forms the superorbital ridge (11'), and articulates anteriorly 

 by a kind of gomphosis with the malar (2G') : it is overlapped here, as 

 on the cranium, by the maxiUary (21"), The medial parts of the 

 frontals are united posteriorly with the interparietal (7*), anteriorly 

 with the nasals (15). 



" The vomer extends forward to within 1^ inch of the end of the 

 premaxillaries, and, behind these, intervenes upon the bony palate 

 between the maxillaries, along a strip of 2 inches extent and 3 lines 

 across the broadest part. This palatal part of the vomer is the 

 lower convexity of the canal formed by the spout-shaped bone : the 

 hollow of the canal is exposed at the upper interspace of the pre- 

 maxillaries. Here also is seen, 2 inches behind the fore end of the 

 vomer, the rough, thick, anterior border of the coalesced prefrontals, 

 which contracts as it passes into their upper border, forming the 

 septum of the nostrils, expanding below and behind to form the 

 back wall of the nasal passages. Here a trace of the suture between 

 these foremost neui'apophyses of the skull remains. The small, 

 transversely extended, subquadrate nasals (15) intervene between the 

 frontals and prefrontals. 



" The palatine bones appear in the palate as narrow strips wedged 

 between the maxillaries and pterygoids, and imited together beneath 

 the vomer by a longitiidinal suture of 3'" in extent : passing out- 

 ward and forward, after a brief contraction, they suddenly expand 

 and bend upward to line or form the mesial wall of the orbit, and 

 again contract to articulate with the frontal, at the superorbital fossa. 

 The mesial borders of the palatines articiilate with the vomer and 

 prefrontals ; and, between the pterygoids and the vomer, the pala- 

 tines form the fore part of the lower half of the nasal passages. 



