1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 31 



region, which is also somewhat imperfectly preserved. The upper 

 surface of the skull is entirely broken away, making- it impossible to 

 determine whether or not this form approached Pontolis magnus and 

 recent Otariidae in the possession of a sagittal crest. 



A comparison of Ettmetopias jubata and other Otariidae with this 

 skull indicates that the occipital region has been somewhat modified 

 in recent forms, though the underlying plan remains the same. Dur- 

 ing the course of time the occipital crest has been reduced in size, and 

 gradually tilted forward or upended until now it no longer projects 

 backward in any of the recent Otariidae. In coordination with the 

 reduction of the lateral crest, the median supraoccipital ridge has also 

 become reduced and persists as a feebly developed ridge, though never- 

 theless distinct in all cases. We find the same condition in Odobenus 

 only carried much further, and accompanied by a crowding backward 

 of the rostral region as well. 



In this connection it is interesting to note that the view of the 



skull given by True 4 indicates that the occipital crest of Pontolis 



mag tins agrees more closely with recent Eumetopias than with this 



skull. The same appears to be true of Desmatophoca oregonensis, 5 



although Thomas Condon 6 stated that : 



The development of the occipital crest can not be determined with absolute 

 certainty as that part of the brain case has been damaged, but it would seem to 

 have been poorly developed as that portion of the occipital bone directly above the 

 foramen magnum slopes forward at an angle of forty-five degrees, and there is 

 reason to believe the general shape of the occipital or lambdoidal crest presented 

 that characteristic U-shaped form of Phooa rather than that of Otaria. 



From the measurements given by Condon 7 and also from his plates 

 one is led to believe that Desmatophooa resembled more closely in size 

 and appearance the recent Zalophus, though, as stated by Condon, it 

 lacked a sagittal crest. . 



On first examination and before the matrix was sufficiently cleared 

 away to reveal their true nature, the occipital condyles appeared to 

 resemble very closely tbe type found in whales, but further study 

 showed that the condyles were entirely broken away. Even in this 

 imperfect condition one of the condyles measures forty-six millimeters 

 in the greatest transverse diameter. The internal portion of the con- 



* True, F. W., Prof. Paper No. 59, U. S. Geol. Surv., pi. 22, Washington, T>. C, 

 1909. 



5 Condon, T., A new fossil pinniped {Desmatophoca oregonensis) from the 

 Miocene of the Oregon coast. Univ. Oregon Bull., vol. 3, suppl. no. 3, pp. 1-14, 

 Eugene, 1906. 



o Condon, T., op ext., p. 7. 



7 Condon, T., op. ext., p. 11. 



