CETACEA. 



[87 



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 



Na IP 



EjcO 



Fig. 61. — A section of the skull of a young Dolphin {Globicephalus melas\ \. PAfx 

 prtmaxilla ; Mx max<lla ; MR ossified poitiun of tne mesethmoid; an anterior 

 nares ; Na nasal ; IP interparietal ; Fr frontal ; Pa parietal ; SO supraoccipital ; 

 ExO exoccipital ; BO basioccioital ; Sq squamosal ; Per periotic ; AS alisphenoid ; 

 PS presphenoid ; Pt pterygoid ; fin posterior nares ; PI pa^tine ; Vo vomer ; 

 * symphysis of mandible; id inferior dental canal ; cp coronoid piocess; erf con- 

 dyle ; a angle ; s/i stylohyal ; bh basihyal ; 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 





