BY W. J. McKAY. 913 



carries one fang firmly fixed bo the bone, while two accessory ones 

 lie embedded in the mucous membrane immediately behind. On the 

 posterior third of this margin there are three small permanently 

 erect teeth. The anterior surface is smooth and convex, with a 

 small depression over the fixed fang. Ov^er this surf ace the venom 

 duct runs to reach the fang. The external su rface is the continua- 

 tion of the anterior; it has a small groove for the venom duct to 

 lie in. The internal surface presents two regions, an antero- and 

 a postero-lateral, and between them a strong process. The antero- 

 lateral is the smaller of the two, and is formed by an excavation 

 of the bone from above downwards and outwards; thus a concave 

 surface is formed in which the palate bone tits. Behind this con- 

 cavity the bone is produced downwards, inwards, and backwards, 

 so that a prominent process is formed which lies on the palate, and 

 is closely connected to that bone by ligament ; the process also 

 receives some of the fibres of the parieto-pal atine muscle. The 

 posterior two-thirds of this side is deeply excavated, forming the 

 postero-lateral fossa. This is chiefly filled by the mucous mem- 

 brane in which the accessory fangs lie. 



The posterior extremity presents an articular surface consisting 

 of a concave surface externally and a convex internally ; it articu- 

 lates with the transverse bone. 



The bone differs from that of Morelia, in which the bone is long 



and prismatic-like, with all the teeth of nearly equal size. From 



Dahoia it differs essentially in having the three solid teeth behind. 



It differs from Diemenia and Pseudechis only in the shape of the 



superior surface, which in these two forms is more concave so that 



the bone may move freely on the anterior orbital. Thus we see 



that this bone alone enables us to decide as to the classification of 



Acantliophis. 



Os Transpalatinum. 



Pterygoideum externum^ D'A.lton, Harting ; Transversum, 

 Cuvier, Joh. Miiller; Os transversum oder dusseres Flilgelbein, 

 Gegenbaur ; Transversum^ Hoff'mann, Huxley, Wiedersheim ; 

 Hinteres Flilgelstiick, Meckel ; Pktopterygoid, Owen, Stannius ; 

 Transpalatinum, Parker, Parker and Bettany. 



