DIET ADAPTATIONS IN VARANUS NILOTICUS. t)7 



been swallowed along with the soft parts. It becomes evident 

 from these facts that Varanus niloticus in Cameroon subsists 

 to a great extent on land-molluscs, the sbells of which are 

 crushed into pieces by the aid of the powerful jaws and the 

 large rounded niolars; and at the same time that the lizard 

 before swallowing the mollusc dröps or shakes off the frag- 

 ments of the shell, or in some way or other cleanses the soft 

 body from the pieces of the shell. It is clear that some such 

 act of cleansing takes place because the few fragments of 

 shell that are left and had passed down into the stomach 

 of the lizard chiefly consist of such parts which have clung 

 more intensely to the body, as for instance the top of the 

 spiral, and pieces of the shell adjoining the columella. It is 

 also quite certain that the relative absence of shell-frag- 



-<*,...*&■ A&&*L 



Fig. 1. Side view of the skull of a Varanus niloticus from Cameroon 



2 /3 nat. siz. 



ments in the ventricle of the Varanus is not due to the dis- 

 solving influence of the gastric juices, because in the cases 

 referred to above the molluscs have been swallowed quite re- 

 cently, so that the gastric juice has had no time either to 

 dissol ve the lime of the shell-fragments or to macerate or de- 

 compose even the most tender parts of the visceral säck of 

 the molluscs. 



The crushing of the shells with the jaws and teeth is not, 

 however, to be compared with the act of masticating the 

 food such as takes place among the mammals for instance. 

 It is only an action that is perpetrated for that special kind 

 of food with a härd shell. The slugs found in the ventricle 



