CETACEA. 



187 



is of great size, and slopes upwards and forwards. The 

 foramen magnum is large, and looks directly backwards ; its 

 lower lateral margins are bounded by large oval condyles? 

 which meet in the middle line below, and are formed by 



i:xO 



BO 



Yu,. 61. — A section of the skull of a young Dolphin {Globicepknhis jiielas), \. PMx 

 prtmaxilla ; Mx max Ha ; ME ossified poition of tne mesethmoid ; an anterior 

 nares ; Na nasal ; IP interparietal ; /V frontal ; Pa parietal ; SO supraorcipital ; 

 E.xO e.xoccipital ; BO basioccinital ; Sq squamosal ; Per periotic ; AS alisphenoid ; 

 I'S presphenoid ; Pt pterygoid ; pn posterior nares ; /-"/ pa'atine ; Vo vomer : 

 .V symphysis of mandible ; id inferior dental canal ; cp coronoid piocess ; cd con- 

 dyle ; a angle ; sh stylohyal , bh bas.hyal ; th thyrohyal. 



the exoccipitals, with a small portion of the basioccipital. 

 Above the foramen, the immense supraoccipital [SO), with 

 which an interparietal {^IP) is ankylosed, extends forwards 

 beyond the vertex, to be wedged in between the frontals, 

 completely excluding the parietals from the upper region of 



