BY W. J. McKAY. 895 



from before backwards and downwards for articulation with the 

 frontals. The antero-lateral border is concave and smooth, the 

 superior portion of the postorbital articulating with it. The middle 

 lateral border is rounded and smooth, the masseter gliding over it. 

 The postero-lateral border runs backwards and inwards. It has a 

 small tubercle dividing it into an anterior third and a posterior two- 

 thirds. The parieto-pterygoid muscle arises in part from the ante- 

 rior third, while the anterior temporal arises from the posterior 

 two-thirds. The anterior extremity of the squamosal abuts against 

 the tubercle. The posterior border is the smaller, and is formed 

 like the anterior of the right and left moieties of the parietal. It 

 is serrated for articulation with'the supraoccipital. 



The superior surface of the parietal taken as a whole is convex. 

 It may be divided for convenience of description into three trian- 

 gles, a median and two lateral. 



The median triangle has its base at the anterior border, and its 

 apex in the mid-line on the posterior border. This triangle is subcu- 

 taneous and concave anteriorly. A dark line is seen in the mid-line, 

 indicating where the two halves have coalesced. In Python a 

 prominent crest may be seen. The greater development of the 

 crest being, as in the Carnivora, for the attachment of the powerful 

 muscles of the mandible, the muscles being much more powerful 

 in these snakes which have to rely on strength, and not on their 

 poison, for self-defence, and for obtaining their prey. 



On either side of the median triangle lies a lateral one. The 

 base of each lateral triangle is irregular, and consists of an antero- 

 and middle- lateral side. The apex is the posterior border. The 

 lateral triangles present a series of concave and convex surfaces. 

 From the inner portion of the triangle the masseter arises, from the 

 outer portion the anterior temporal, and part of the parieto- 

 pterygoid. 



Where the middle lateral joins the postero-lateral border a 

 well marked prominence of bone is developed, and from this and a 

 portion of the superior surface the parieto-mandibular muscle 

 arises. 





-• i» ^ I:; R A R Y; ^ 



