BY W. J. McKAY. 899 



connection whatever with the prefrontal. In Pseudechis there is 

 a slight connection between the two bones, but in Dahoia there 

 is no other connection than by the membrane that bridges over 

 the space left between the two bones. It is plain from the above 

 arrangement that the prefrontal has a much more extended range 

 of movement in the venomous forms than in the non-venomous. 



Os Pr^maxillare. 



Inter maxillare^ D'Alton, Cuvier, Harting ; Proimaxillare, Gegen- 

 baur, Huxley, Owen, Hoffmann, Parker, Parker and Bettany, 

 Wiedersheim ; Ztvischen Eiefer, Stannius, Meckel. 



The premaxilla is a T-shaped bone. The superior surface is 

 smooth and convex, and runs upwards and backw^ards to form a 

 nasal process which articulates with the vertical septum of the 

 nasals. The inferior surface is horizontal and forms the anterior 

 portion of the roof of the mouth. Posteriorly it is continued back 

 to form a bifurcated palatine process. Between the inferior and 

 superior surfaces there are small lateral plates to which the septo- 

 maxillary bones are articulated. It contains no teeth. 



The bone closely resembles the premaxilla of Python, and of 

 other forms examined. The chief difference to be noticed between 

 the bones of the non-venomous and the venomous snakes is the 

 relation of the premaxilla to the maxilla ; owing to the latter bone 

 in the non-venomous forms being much longer it approaches 

 close to the premaxilla and is united to it by fibrous tissue. 



Os Septo-maxillare. 



Ethmoideu7n, D'Alton, Wiedersheim ; Cornet inferieur, Cuvier ; 

 Turhincd hone, Huxley, Owen ; Riechhein, Leydig, Meckel -, 

 Se2?to-maxUlare, Parker, Parker and Bettany ; Concha, Stannius ; 

 Septo-maxillare, Hoffmann. 



The se|)to-maxillary bones are two small shells on either side of 

 the nasal septum. Each has a small vertical portion and a larger 

 horizontal plate. The horizontal plate is triangular in outline, the 



