NO. 2 A MIOCENE LONG-BEAKED PORPOISE— KELLOGG 5 



the maxillary notch and whose styliform process is extended back- 

 ward beneath the orbit to the anteroventral angle of the zygomatic 

 process where it is expanded into a broad thin plate. The jugal was 

 unavoidably removed while the skull was being freed from the 

 matrix. 



The zygomatic process of the squamosal is thickened dorso- 

 ventrally and is almost in contact anteriorly with the postorbital angle 

 of the supraorbital process. As a whole the zygoma is robust, slightly 

 curved, and rather long ; the dorsal profile slopes gradually forward 

 and upward. The postglenoid portion of the zygoma curves down- 

 ward and then forward. The greatest length of the left zygoma is 

 90 mm. and the dorso-ventral diameter anteriorly is i8 mm. 



The crest formed by the contact of the supraoccipital with the 

 hinder ends of the frontals is destroyed but it was presumably the 

 highest point in the dorsal profile. The dorsal profile of the skull 

 slopes rather steeply from the vertex to the level of the maxillary 

 notches. On each side of the vertex, the frontal plate of the maxil- 

 lary is depressed. The supraorbital process of the frontal and the 

 superimposed maxillary do not rise above the level of the premaxil- 

 lary in front of the narial passages. The temporal fossa is much 

 longer than the orbit. In the temporal fossa the parietal is suturally 

 united inferiorly with the squamosal, anteriorly and superiorly with 

 the frontal, and posteriorly with the supraoccipital. Hence the parie- 

 tals are excluded from the vertex of the skull. When viewed from 

 the side, the occipital condyles are seen to project considerably be- 

 yond the level of the hinder surfaces of the exoccipitals. The basi- 

 cranial axis is bent downward from the axis of the rostrum. 



Posterior viczv. — This surface (pi. 3) attains its greatest breadth 

 at the level of the exoccipitals. These exoccipitals are relatively large, 

 are coalesced with the supraoccipital above, and are projected out- 

 ward and backward like wings. Their external margins are sinuous- 

 rounded, and are produced outward so that they conceal for the most 

 part the postglenoid processes when viewed from behind. Anteriorly 

 the exoccipital is in contact with the squamosal and inferiorly it is 

 united with the basioccipital. The suture between the exoccipital and 

 the basioccipital lies internal to the deep jugular incisure and the 

 former constitutes the hinder border of the falcate process of the 

 latter. At the bottom of this incisure and near the posterior margin 

 there is a small condylar foramen. Externally the upper portion of 

 the exoccipital is produced backward, forming a crest which follows 

 the curvature of the hinder end of the temporal fossa. This thin- 



