124 THE SKULL [chap. 



and by its upper end firmly ankylosed with the surround- 

 ing bones. It can be seen much more distinctly in some 

 dogs' skulls than others, and is more conspicuously de- 

 veloped in some other Mammals. This I have called iyin- 

 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 cavity. 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 

 anterior hyoidean arch, the stylohyal {sh). The two suc- 

 ceeding bones {ep and ch) are named by Professor Owen 

 respectively epihyal and ccratohyaL All three are elon- 

 gated, compressed, slighdy 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 {bh) is a transversely-extended, flattened bar, 

 with its extremities rather upturned and thickened. The 

 posterior cornu {tJi) consists of a single, nearly straight, 

 compressed bone, the thyrohyal, articulated inferiorly witli 

 the outer end of the basihyal, just below the attach- 

 ment of the ceratohyal, and truncated at its superior ex- 

 tremity, to which the thyroid cartilage of the larynx is 

 suspended. 



Dei^elopment of the Skull. — For a detailed and beautifully 

 illustrated account of the early development of the T^Iam- 

 malian skull, I must refer to Professor Parker's monograph 

 " On the Structure and Development of the Skull in the 



