72 ARKIV FÖR ZOOLOGI. BAND 1. 



animals of comparatively large size as otlier lizards, rodents 

 etc, which must be caught by rapid movenients and tlien, as 

 is the habit of the lizard, shaken to death before swallowed. 

 In such a case the connection between the skull and the body 

 must be at the same time strong and highly movable. But this 

 is not in the same degree needed by V. niloticus, which to 

 a great extent feeds on sluggish molluscs not requiring such 

 a treatment. 



If we now proceed in a forward direction with the com- 

 parison of the lower surface of the two skulls it must beobserved 

 that the basipterygoid-processes of the basisphenoid have r 

 in the two lizards, such a different direction. In V. salvator 

 they are chiefly directed laterally, although somewhat for- 

 ward and downward. In V. niloticus their chief direction 

 is downwards although at the same time obliquely towards 



Fig. 3. Palatal aspect of the skull of Varanus niloticus from Cameroon. 



V 3 nat. siz. 



the sides. In the former these processes are slightly longer 

 but simultaneously more slender so that their breadth distally 

 measures about 10 but in the latter 13 1 / 2 mm. As the ptery- 

 goidea lean on those processes and are held apart by them 

 the different direction of the processes, as mentioned above, 

 produces a great difference in the position of the pterygoidea 

 In V. salvator (conf. hg. 4) with laterally directed processes there 

 is in front of the same a väst aperture between the pterygoidea 

 measuring not less than 21 mm., but in V. niloticus with down- 

 wards directed processes (conf. fig. 3) the same interspace is nar- 



