AHT. 15 ANATOMY OF THE EAEED AND EAELESS SEALS HOWELL 



15 



of the bone. The latter description fits the condition in Phoca 

 hispida. In the Zalophus the paroccipital-mastoid process begins at 

 the posterior lacerated foramen and extends caudo-laterad. The 

 crest then turns and extends craniad, broadening abruptly and ending 

 as the caudal boundary of the external auditory meatus. Even in 

 the subadult skull there is no indication whatever of a distinct 

 mastoid, it having to all intents disappeared in the parietal-occipital 



premax. 



F. IMFHAORB 



/AAX. NASO-LAB. • 



,^\ASS. SUPERF. 



/^ASS. PKOf. 



palit^' 



vomer- 



prespHen 



pterygoid^ 



alisphi 



/AEATUS AUD\ 



squamosal 



taSLSphen^ 



bcisloccip 



F. STY LO^\AST 



F. cAncrriD 



T. U\CtT\Uf^ POSX- 



?. CONDYb 



•TRACHtLOfAKST. 



STERN OlAA'iT. 

 DyGASTRlC. 

 ■RECT. CKP.ANT. K\nW 

 \T\ECT. CKP.ANT. r^A3. 



Fig. 5. 



-Ventral view of the skull of Phoca hispida; names of bones in small 



TYPE 



fusion. In Phoca hispida there is the slight swelling denoting the 

 position of the paroccipital process, and from this, a lateral bulge of 

 the somewhat inflated mastoid, nonmuscular in character, to the 

 moderately developed mastoid process located caudad of the bony 

 lip of the auditory meatus. As previously inferred, in those phocids 

 which have prominent paroccipital processes there is no continuous 

 prominence from this to the mastoid process. In a fetal Phoca vitu- 



