BY W. J. McKAY. 939 



soft parts. We consider that the parieto-pterygoid represents the 

 tensor palati ; while the spheno-pterygoid represents the levator 

 palati, the parieto-palatine being a differentiated portion of the 

 tensor. The change in these muscles has been brought about by 

 the position taken by the pterygoid bone, it having encroached on 

 the region where normally the tensor and levator palati have an 

 insertion into fibrous membrane only. Regarding the nerve 

 supply, which is somewhat difficult to make out, the parieto- 

 pterygoid is supplied by a nerve that issues from an aperture in 

 the alisphenoid, and occupies such a position relative to the fifth 

 as a nerve coming from the otic ganglion would. 



The spheno-pterygoid appears to be supplied from the seventh. 



SuB-occiPiTAL Articular. 



Sub-occipital articular, Duges, Duvernoy, Owen, and R. Jones ; 

 not mentioned by D'Alton or Hoffinann. 



The muscle springs from the posterior portion of the basi- 

 sphenoid and the anterior part of the basioccipital. It passes 

 outwards and backwards to be inserted on the middle third of 

 the posterior border of the quadrate. As the muscle runs out- 

 wards it lies as a thin sheet on the posterior portion of the spheno- 

 pterygoid muscle ; while the dorsal muscles lie internal to it. 



The two sub-occipital articular muscles are described as con- 

 stituting an azygos muscle. There are, however, two distinct 

 muscles, each arising as stated above. Again, the muscle is not so 

 closely related to the quadrato-mandibular joint as the name would 

 seem to imply. 



A similar muscle is described by Sanders (25) in Platydactylus 

 japonicus, and in Liolepis belli, whilst we have found it to be 

 present in Hydrosaurus. Sanders considered it to represent the 

 laxator tympani, while Owen compares it to the depressor tympani 

 of fishes. We, however, think that, if the muscle is tympanic in 

 nature, it will represent the tensor tympani. 



