LÖNNBERG, STUDY OF THE VARIATION OF EUROPEAN BEAVERS. 15 



towards the base of the molar than the two other lateral 

 folds and their products are therefore visible in a låter age 

 on the worn surface of the molar than those of the latter. 

 The anterior and posterior outer folds make, however, at 

 their basal end a dip inwards which extends somewhat deeper 

 than the fold does at the surface. This causes that, when 

 the molars are sufficiently worn, the connection with the 

 superficial enamel laj-er is broken off and the enamel of these 

 (anterior and posterior) folds appear on the worn surface of 

 the molar in the shape of detached short transverse folds or 

 small ring-shaped islets (conf. fig. 4) before they completely 

 disappear. 



A list of measurements is appended from which it may 

 be seen that some dimensions of the Beaver skulls are rather 

 variable. 



