36 PROCEEDINGS OF THE NATIONAL, MUSEUM vol. GO 



Measurements of the skull — Continued 



mm. 



Greatest breadth of left premaxilla in front of nares 41 



Greatest breadth of left premaxilla at maxillary notch 29. 2 



Breadth of rostrum at maxillary notches 118 



Breadth of rostrum at extremity 19. 2 



Length of frontal plate of left maxilla 152. 3 



Greatest breadth of left maxilla posterior to nasals 66 



Distance between inner margins of maxillae at vertex 56. 8 



Greatest thickness of frontal and maxilla combined near center of orbit- 17. 3 



Maximum width of exposed portions of combined frontals on vertex 75 



Greatest length of exposed portion of left frontal at vertex 25 



Anteroposterior diameter of left nasal (along suture) 21.5 



Greatest anteroposterior diameter of right nasal 28. 3 



Transverse diameter of right nasal 21. 2 



Distance from vertex to upper margin of foramen magnum 102. 7 



Greatest height of left condyle 41 



Greatest breadth of left condyle 26 



INDIVIDUAL 4 



Skull, Cat. No. 10711, Section of Vertebrate Paleontology, United 

 States National Museum. 



From time to time large masses of clay are dislodged from the 

 cliffs by the undercutting action of the tides. Whenever remains 

 of fossil cetaceans are thrown down in this manner they are usually 

 broken up either by the fall or by being rolled about in the water. 

 It is not known whether this skull was broken in this way or at the 

 time of excavation. At any event the skull was fractured in many 

 places and was restored to its present condition before it was pur- 

 chased by the museum. It is listed here on account of the large 

 size of the braincase. On the basis of comparative measurements 

 taken from the other skulls it is apparent that only the proximal 

 one-third of the rostrum is preserved. As will be noted from an 

 examination of plate 17, the outer margins of the maxillae anterior 

 to the maxillary foramina have been broken off along the external 

 margins of the premaxillae. The thin horizontal plate of the left 

 maxilla is fairly well preserved above the temporal fossa and re- 

 tains most of its original external margin, but on the right side 

 posterior to the supraorbital process a large section of the maxilla 

 is missing, exposing the temporal fossa. 



A section of the right premaxilla, 46 mm. in length, is missing 

 above the nasal passage and the inner margin of the left is imperfect 

 in the corresponding region. Both nasal bones are lost. A very 

 narrow strip of the combined frontals is exposed on the vertex. 

 Part of the thin horizontal plate of the maxilla which overlies the 

 right supraorbital process is missing. The slender process of the 

 maxilla which projects forward and overlies the left lachrymal Avas 



