122 



Basic Structure of Vertebrates 



Table 1 

 Chief Bones of Skull of Becent Vertebrates 



Cartilage bones are in bold-face type; dermal bones in italics. 



I, bones which are lateral and paired; m, a median bone. AH bones not otherwise designated are 

 lateral and paired. 



* Cartilage bone more or less augmented by addition of dermal bone. 



t A name which (with appropriate orefixes) applies to two or more bones which are closely related 

 in origin and position: e.g., mesethmoid, ectethmoid; entopterygoid, metapterygoid, etc. 



X Homology of alisphenoid and vomer of mammals with alisphenoid and vomer, respectively, of 

 lower vertebrates is questionable. 



§ The position of the jugal is ambiguous. Its dorsal edge commonly forms more or less of the 

 ventral border of the orbit (Fig. 121). Therefore it may be regarded as a circumorbital bone. 



(Modified from Rand, "Comparative Anatomy of Vertebrates," Harvard University Press, 1929.) 



