xoT FUSION- OF ‘CERVICAL VERTEBRAE 351 
developed supra-occipital in the adult. Here again the Zeuglo- 
donts are more typically Mammahan, for in them the parietals 
have a normal development and situation, rising even into a 
median crest as in so many quadrupeds. The bones related 
to the organ of hearing, the tympanics and petrous bones, are 
very solid and dense in structure. Moreover they are but 
Na Tar, 
. Fr 
Fig. 185.—A section of a skull of a young Caa’ing Whale (Globicepnalus melas). x4. a, 
Angle ; av, anterior nares ; AS, alisphenoid ; bh, basihyal ; BO, basioccipital ; BS, 
basisphenoid ; cd, condyle ; cp, coronoid process ; HxO, exoccipital ; Fr, frontal ; 
id, inferior dental canal; //, interparietal ; J//, ossified portion of the meseth- 
moid ; Mx, maxilla; Ma, nasal; Pa, parietal ; Per, periotic ; Pl, palatine ; PM2a, 
premaxilla ; pr, posterior nares ; PS, presphenoid ; Pt, pterygoid ; s, symphysis 
of mandible ; sh, stylohyal ; SO, supra-occipital ; Sq, squamosal ; th, thyrohyal ; 
Vo, vomer. (From Flower’s Osteology. ) 
loosely attached to surrounding bones, and are thus easily and 
frequently lost. Nearly the only mammals which resemble the 
Whales in the fact that the pterygoids sometimes meet in the 
middle line below are the Edentata (Anteater and Armadillo, see 
p. 167). But in both groups this peculiarity is not universal. 
The vertebral column is remarkable for the fact that more or 
fewer of the cervical vertebrae may be fused together into a short 
and compact mass. This is seen at its maximum in the genera 
Balaena and Neobalaena. The odontoid process of the second 
