350 NASAL BONES CHAP. 
phins and, especially, Physeter. 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 
\ 
PUL 
Fra. 184.—Under surface of the cranium of a young Caa’ing Whale (Globicephalus 
melas). <4, AS, Alisphenoid ; BO, basioccipital ; cf, condylar foramen ; 4x0, 
exoccipital ; /’r, supra-orbital process of frontal ; g/, glenoid fossa of squamosal ; 
Ma, body of malar ; Mz, maxilla ; OS, orbitosphenoid ; Per, posterior (mastoid) 
process of periotic ; P/, palatine ; PM, premaxilla ; P¢, pterygoid ; Sg, squamosal ; 
tg, deep groove on squamosal for meatus auditorius externus, leading to tympanic 
cavity; Zy, tympanic; Vo, vomer; 7M, zygomatic 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- 
