METEIOKHIXCHUS. 



159 



while below it joins a process of the angular, forming with that bone the inner border 

 of the widely open dental canal. 



The articular (art.) is a massive bone. The surface for the quadrate consists of two 

 concavities separated by a low oblique ridge: on the outer side the articular surface is 

 completed by a thickening of the surangular; on the inner side, a little behind the 

 articular surface, the border is produced inwards into a prominent process terminating 



Text-fig. 61. 



aiv.U od. 



Atlas and axis of MetriorJiyncIius : A, atlas and axis of (?) M. superciliosum, with ribs, from left side (Leeds 

 Coll., 4 nat. size) ; B, atlas and axis of M. cultridens, from left side ; C, ditto from below (It. 3S04, 

 i nat. size). 



nt.n., arch of atlas ; a.w.b., anterior wedge-bone ; a.v.a., arch of axis ; d., diapophysis ; /., median furrow in 

 odontoid ; od., odontoid ; p.:., jiosterior zygapopliysis ; r.l., rib of atlas ; r.2., rib of axis ; r.l.f., facet 

 for first rib ; r.2.f., facet for second rib. 



in a rugose surface. Behind this the bone narrows to the postarticular angle ; in this 

 region the upper surface is gently concave on each side of a low longitudinal convexity. 



