DIET ADAPTATIONS IN VARANUS NILOTICUS. 75 



But at tlie same time it must not be forgotten that the 

 heaviness of the anterior part of the skull of V. niloticus 

 in connection with its function requires a stronger bracing 

 apparatus and a finner connection with the posterior part 

 of the skull and this is also effected by the arrangement 

 described above and by the increased stoutness of the sup- 

 porting bones. 



The articulation betwee.n the lower jaw and the skull 

 is of course through the greatly increased breadth as well 

 of articulare as of quadratum much firmer in V. niloticus 

 than in V. salvator, but at the same time the construction 

 of the articulation in the former is strengthened by a posterior 

 ridge that borders the articular surface of the mandible. 



It remains to say a few words about the teeth of V. 

 niloticus. The teeth of the premaxillary and corresponding 

 parts of the mandible (conf. figs 1 and 3) are comparatively 

 small, bluntly conical in shape and not much different from 

 those of V. salvator (figs 2 and 4). The three or four teeth 

 following next in the maxillary may still be termed conical 

 although very blunt and stout approaching the cylindrical 

 shape.* The following teeth are as thick at the free as at 

 the fixed end, with completely rounded tops (conf. fig. 1). 

 They increase in size backwards, but the two most posterior 

 ones are again somewhat smaller. The largest ones in this molar 

 series are not quite cylindrical, but obliquely compressed in 

 such a way that their longest transversal diameter is directed 

 obliquely backwards and towards the median line (conf. fig. 3).. 

 Thanks to this somewhat compressed shape a larger number 

 of teeth can obtain place in each series than if they where 

 cylindrical, which is of importance as the teeth are changed 

 rather of ten. As it is now the jaw is not made ineffective 

 even if some of the teeth have fallen out, which otherwise 

 might easily be the case as the empty interspace would be 

 too wide. The oblique position is of course also useful for 

 this same purpose. 



It is interesting to see how, in consequence of the great 

 basal enlargement of the molars, the hindmost molar has 

 expanded över from the maxillary to the palatine so that 

 the fully developed last molar is based as well on the 



* It is to be observed that several teeth especially in the mandible have 

 fallen out in the skull fi<mred. 



