NO. 2 A MIOCENE LONG-BEAKED PORPOISE — KELLOGG 7 



The relations of the pterygoids with the surrounding bones is essen- 

 tially in agreement with that of Eurhino del phis bossi. The external 

 reduplication of the pterygoid is for the most part destroyed. Rem- 

 nants of the ends of the outer plate on the left side show that the 

 internal and external plates of the pterygoids are separated from 

 each other by a narrow interval anteriorly, but posteriorly they are 

 widely separated. Hence the usual pterygoid sinus must have been 

 present. The curved internal plate contributes the lower outer sur- 

 face for the narial passage. The combined internal and external 

 plates of the pterygoid seemingly contribute to the formation of the 

 elongated, backwardly projecting hamular process which constitutes 

 a posterior extension of the palatal surface. The anterior margin of 

 the external plate of the pterygoid is united by an irregular suture 

 with the palatine. The external plate of the pterygoid is suturally 

 united with the squamosal and palatine, and apparently is in contact 

 with the parietal and alisphenoid. 



The outer wall of the cranium in the region of the alisphenoid and 

 orbitosphenoid is imperfect. The optic canal, while seemingly con- 

 fluent with the sphenorbital fissure, nevertheless has its course marked 

 by a definite groove. This canal should be bounded anteriorly near 

 its origin by the descending portion of the orbitosphenoid. 



A recess is formed by the backward extension of the alisphenoid 

 (PI. 4) and the contiguous underlying lateral process of the basi- 

 occipital, which completely excludes the periotic and tympanic from 

 the inner wall of the cranium. On the roof of this recess and near 

 its posterior end is a large orifice that corresponds to the foramen 

 lacerum posteriiis for the nerves associated with the jugular leash. 



The thin descending plates or falcate processes of the basioccipital 

 are directed downward and outward ; anteriorly they are suturally 

 united with the internal plates of the pterygoids which overlap the 

 basisphenoid. 



The distinguishing features of the squamosal are the large size and 

 strength of the zygomatic arch, the short robust postglenoid process, 

 and the thin falciform process which is directed forward and down- 

 ward in front of the tympano-periotic recess. The zygoma is rather 

 large and is directed slightly outward. The ventral glenoid surface is 

 an oval concavity, looking forward, inward, and downward. A nar- 

 row groove for the external auditory meatus traverses the squamosal 

 behind the postglenoid process. The hinder end of the squamosal is 

 suturally united with the exoccipital and between this suture and the 

 transverse groove for the external auditory meatus a rounded tuberos- 



