350 



NASAL BONES 



phins and, especially, Physcter. This asymmetry affects parti- 

 cularly the premaxillae, the maxillae, and the nasals. The 

 base of the skull is symmetrical. The Whale's skull has very 

 long premaxillae which, however, do not, except in the extinct 



FIG. 184. Under surface of the cranium of a young Ca.a'iiig Whale (Globicep/talus 

 melas). x . AS, Alisphenoid ; BO, basioccipital ; cf, coudylar foramen ; xO, 

 exoccipital ; Fr, supra-orbital process of frontal ; gf, gleuoid fossa of sqiiamosal ; 

 Ma, body of malar ; MX, maxilla ; OS, orbitosphenoid ; Per, posterior (mastoitl) 

 process of periotic ; PI, palatine ; PM;c, premaxilla ; Pt, pterygoid ; Sq, squamosal ; 

 tg, deep proove on squamosal for meatus auditorius externus, leading to tympanic 

 cavity ; Ty, tympanic ; Vo, vomer ; ZM, zygomatie process of malar. (From 

 Flower's Osteology.) 



Zeuglodonts, bear any teeth. The nasal bones, whether sym- 

 metrical or the reverse, are very small in existing Whales, 

 which arrangement, together with the long and broad maxillary 

 bones, removes the anterior nostrils, the blow -hole, far back- 

 wards. The roof of the skull is not at all formed by the 

 parietals externally. These bones form a portion of the side 

 of the cranium, but are replaced or covered by the enormously- 



