ART. 15. A NEW GEXUS OF WHALE FROM MARYLAND KELLOGG. 7 



tween the basioccipital and the basisphenoid does not show on plate 

 4, but close scrutiny of the exposed surfaces shows that this trans- 

 verse suture lies between the base of the V-shaped fracture and the 

 anterior margins of the subhemispherical protuberances. The occi- 

 pital condyles do not project backward as far as the plane of the ex- 

 occipitals. A groove, which originates within the cranial cavity, 

 follows down the external face of the basioccipital, makes a broad, 

 deep channel on the basioccipital and exoccipital, and terminates on 

 the posterior margin of the last mentioned bone. This is interpreted 

 to represent the posterior lacerated foramen. 



The basisphenoid is a flat bone and may have been largely con- 

 cealed by the vomer. No pieces of the vomer were preserved with 

 this skull. The vaginal plates of the internal pterygoids are not pre- 

 served in their entirety, but the one on the right side overspreads a 

 portion of the basisphenoid. It is suturally united above with the 

 external pterygoid. The internal pterygoid as originally preserved 

 Avas in contact with the supraorbital process of the frontal, touching 

 the descending anterior wall of the optic canal near the base of that 

 structure. An examination of the interior of the cranium shows that 

 two processes arise from the anterior end of the basisphenoid, one of 

 which, the ala temporalis, projects upward and outward and its 

 extremity appears in the temporal fossa as a small element (quad- 

 rangular in outline) wedged in between the squamosal, parietal, and 

 pteiygoid ; the other process, the external pterygoid," appears in the 

 internal wall of the temporal fossa, and apparently forms the floor 

 for the scaphoid fossa. The roof of the scaphoid fossa is formed in 

 part by the basisphenoid and the overspreading external pterygoid. 



The internal pterygoid terminates posteriorly in front of the lat- 

 eral protuberance of the basioccipital. The curvature of the descend- 

 ing portion of the internal pterygoid and the position of the suture 

 which marks its contact with the external pterygoid supports the 

 view that the hamular processes would be reduced or even absent. 



The zygomatic process of the squamosal is slender in Paneto- 

 halaencu but not strongly arched, and hence the jaw articulation 

 would be limited in extent. In skulls of the living species of Balae- 

 noptera^ especisLllj Balaetiopferaborealis, there is within the temporal 

 fossa a deep crease in the anterior margin of the squamosal. This 



8 In an article which appeared after this description was accepted for publication, 

 Ridewood (Philos. Trans. Roy. Soc. London (B), vol. 211, pp. 260-266. 268, text figs. 

 14, 15. May, 1922) points out that Schulte (Mem. Amer. Mus. Nat. Hist., New York, 

 new ser., vol. 1, pt. 6, pp. 476-477, pi. 54, fig. 2, pi. 55, fig. 2, March, 1916) has incor- 

 rectly interpreted the so-called external pterygoid bone and scaphoid fossa. Schulte 

 distinguishes two pterygoid bones separated from each other by a suture. Ridewood 

 maintains that Van Kampen (Morphol. Jahrb., Leipzig, vol. 34, Heft 3-4, p. 649, De- 

 cember, 1905) has correctly interpreted the parts under discussion. According to the 

 latter, the pterygoid bone has pushed its way in between the alisphenoid and squamosal 

 .and thus forms part of the internal wall of the temporal fossa. In consequence, the 

 pterygoid bone by itself bounds the pterygoid fossa [=scaphoid fossa of Schulte] 

 anteriorly. 



