144 THE SKULL [CHAP. 



developed in some other Mammals. This I have called tym- 

 panohyal, as it is always in relation with the hinder edge 

 of the tympanic bone, generally more or less surrounded by 

 it, and it extends upwards, embedded in, and afterwards 

 ankylosed with, the periotic, to the hinder wall of the 

 tympanic caviiy. Its lower end is truncated and con- 

 tinued into a band of cartilage, which connects it with 

 the proximal end of the bone which has been generally 

 recognised as the uppermost of the series forming the 



6/i 



FIG. 50. Extracranial portion of hyoidean apparatus of Dog, front view, sh stylo- 

 hyal ; eh epihyal ; ch ceratohyal (these three constitute the "anterior cornu"); 

 b'k basihyal or " body " of hyoid ; th thyrohyal, or "posterior cornu." 



anterior hyoidean arch, the stylohyal (s/i). The two suc- 

 ceeding bones (ep and ch} are named by Sir Richard Owen 

 respectively epihyal and ceratohyal. All three are elon- 

 gated, compressed, slightly curved or twisted on them- 

 selves, tipped at each end with cartilage, and connected 

 with each other by synovial joints. The stylohyal and 

 epihyal are nearly equal in length, the ceratohyal shorter 

 and stouter. 



The basihyal (bit] is a transversely-extended, flattened bar, 



