302 MYOLOGY OF CHLAMYDOSAURUS KINGII, 



and is inserted into the middle of the inner side of the thyrohyal. 

 The greatly elongated thyrohyal passes between the two layers of 

 integument constituting the hood, at its middle fold, and so forms 

 a " yard " to which the lower half of the hood is bent. This 

 inner division of the Thyromandibularis being an adductor of the 

 bone, is the chief agent in lowering the hood and bracing its lower 

 moiety to the side of the neck — it is antagonised by the greater 

 part of the outer division which rises fleshy immediately behind 

 the inner one, but nearly on the lower edge of the jaw, the origin 

 of the mylohyoideus being between them It immediately divides 

 into two superposed fascicles, the deeper one being inserted into the 

 lower surface of the thyrohyal a little behind the insertion of the 

 inner division — the other sub-division is inserted posteriorly to the 

 former one into the outer side of the bone for the rest of its length, 

 and acting thus advantageously is an efficient erector of the lower 

 part of the hood. 



Geniohyoideus (fig. 1 — g. h.) — Partly concealed by the preceding 

 rises as a fleshy cone from the symphysis, and expanding as it 

 recedes, is inserted into the inner side of the base of the thyrohyal. 



Ceratomandibular (tig. 1 — c. m.) — Rises by a double headed 

 origin from the inner side of the mandible below the thyroman 

 dibularis — and is inserted into the whole of the outer side of the 

 cerato-hyal to its extremity. 



Glossohyoideus. — From the mandible, between the symphysis 

 and the insertion of the thyromandibularis— from the median 

 raphe — the outer edge of the under surface of the tongue, the side 

 of the basi-hyal and strongly from the hinder end of the base of 

 the tongue — inserted into the outer side of the proximal portion of 

 the thyrohyal as far backward as the insertion of the outer division 

 of the thyromandibularis— a powerful divaricator of the thyrohyal s 

 and consequent erector of the hood. 



Hyobranchialis (fig. 1, h. b.) — From the hinder edge of the 

 arm of the ceratohyal to the whole of the inner edge of the thyro- 

 hyal beneath the glossohyoideus — the deepest of the muscles 

 concerned in the erection of the frill. 



