896 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



The inferior surface presents four concavities, an anterior 

 pair for the cerebral hemispheres, and a posterior pair for the optic 

 lobes. Posteriorly the surface is much bevelled from behind, 

 downwards and forwards, so as to rest on the supraoccipital and 

 epiotic bones. 



The lateral 'plates of the parietal run downwards and inwards ; 

 both plates begin above at about the junction of the anterior with 

 the antero-lateral edge, and run back as far as the tubercle on the 

 postero-lateral edge. 



The external surface presents anteriorly a deep concavity which 

 contains the lachrymal gland and a part of the orbit ; and poste- 

 riorly another concavity from the upper part of which the parieto- 

 palatine muscle arises, and from the lower portion the spheno- 

 vomerine. A well marked ridge separates these concavities, and 

 to this is attached the fascia covering in the lachrymal gland. The 

 ridge if followed up is seen to end in the prominent projection 

 above, and to this is attached a band of fascia covering the poison 

 gland. The internal surface of the lateral plate is concave for the 

 optic lobes. The anterior border is irregular, with splints of bone 

 for articulation with the frontal and orbitosphenoid. A semi- 

 circular excavation represents the posterior portion of the optic 

 foramen. The posterior border is triangular in outline ; it is 

 rough for articulation with the prootic. 



The inferior border is bevelled from above downwards and out- 

 wards, for articulation with the basisphenoid. The parietal arti- 

 culates with the f rentals, postorbitals, squamosals, prootics, epiotics, 

 supraoccipital, basisphenoids, and orbitosphenoids. 



The parietal differs from the bone of Fytlion in not having 

 a median ridge ; it differs from all the forms examined in having 

 the well marked lateral process. 



Os Frontale. 

 Os Frontale^ all authors. 



The frontal bones are not anchylosed to one another. Each 

 presents a horizontal and a lateral plate. The horizontal plate is 



