84 



MR. E. G. BOULENGEK ON A 



posterior fang-like teeth, the series culminating in such forms as 

 show the maxillary bone much abbreviated, the solid teeth re- 

 duced to two or three only, and the fangs extremely large and 

 grooved. The latest contribution to the subject is one by 

 Mr. John Hewitt *, who attempts to show that the Yiperidse are 

 not of Opisthoglyph ancestry, but are more closely related to the 

 Proteroglyphs. The most important arguments he uses to estab- 

 lish his point are that, in the first place, in the Opisthoglyphs the 



Text-fia;ure 1. 



^-pif. 



rnoc. 



Maxillary (mx.) of Xenodon merremi at rest (A), and erected (B). 

 ept., ectopterygoid ; orb., orbit ; y>rf., prefrontal; ftf., postfrontal. 



fang-bearing portion of the maxilla is situated far behind the 

 prefrontal, and consequently that as there appears to be no 

 tendency amongst Opisthoglyphs for a forward movement of the 

 fang-bearing portion, it is difficult to conceive how the evolution 

 of the Viperine character commenced ; secondly, that in the 

 Proteroglyphs the fang-bearing portion of the maxilla is some- 



* Ann. Transvaal Mus. iii. 1911. 



