902 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



extremity of the parasphenoid becomes compressed and knife-like, 

 wedging in between the hinder ends of the vomers " (Parker). 



The posterior extremity of the basisphenoid is broader, and from 

 its middle point a quadrilateral outgrowth of bone springs. This 

 is bevelled from above downwards and backwards, and is overlapped 

 by the inferior surface of the basioccipital. The sides of the basi- 

 sphenoid are bevelled from above downwards and outwards so as 

 to articulate with the parietal above, and the prootic and ali- 

 sphenoid. The parasphenoid articulates with the vomers, frontals, 

 and basisphenoid. The basisphenoid with the lateral plates of the 

 parietal, the prootics, basioccipital, parasphenoid, and alisphenoid. 



Os Basioccipitale. 



Corpus ossis occijntalis, D' Alton, Kallmann ; Occlpitale basilare, 

 Cuvier, Gegenbaur, Wiedersheim, Hoffmann, Stannius ; Occipitale 

 basilare vd inferius, Harting ; Basioccipitale, Huxley, Parker, 

 Parker and Bettany ; Korper des Hinterhauptstilckes, Meckel ; 

 Occipitale inferius, Joh. Muller, Owen ; Grundtheil des llinter- 

 haup>ibeins, Rathke. 



The basioccipital bone is an irregular hexagon. The anterior 

 border is vertical for articulation with the basisphenoid. The 

 antero-lateral side is rough for articulation with the opisthotic and 

 prootic ; it runs outwards and backwards. The postero-lateral 

 runs inwards and backwards, and articulates with the prootic and 

 exoccipital. The ])osterior border constitutes the lower portion of 

 the occipital condyle ; below it is rounded, above it is grooved in 

 the mid-line and bevelled from above downwards and outwards so 

 as to receive the two processes from the exoccipital, which complete 

 the trefoil-shaped condyle. The inferior surface is divided into an 

 anterior and a posterior part by a transverse ridge. Tlie anterior 

 of the two portions has the suboccipital articular muscle attached 

 to it. There are four spines projecting backwards from the ridge 

 between these two portions. The median pair give insertion to 

 the inferior part of the rectus capitis anticus of either side. The 

 lateral pair give attachment to the superior part of the rectus 



