CH. l] DISTRIBUTION AND STRUCTURE. 25 



sideration is to be qualified by the fact that no casso- 

 wary with a laterally compressed casque (another 

 character made use of by Mr Sclater) exists in New 

 Guinea. In all the New Guinea species the casque is 

 transversely compressed. 



Classification and Distribution. 



The facts of distribution are constantly liable to be 

 misunderstood through ignorance of classification. Not 

 only is a serious error in the actual facts of the distribution 

 of a particular group caused by wrongly assigning to it 

 some individual genus or species, but the significance 

 of the facts is by this largely, sometimes totally, obscured. 

 A knowledge of comparative anatomy is absolutely 

 essential to the student of distribution. It used to be 

 supposed that the central American Carnivore Bassaris 

 was a member of the family Viverridse ; the genus 

 therefore was believed to be the only Viverrine found in 

 the New World, a singular anomaly in the distribution of 

 the group. But Sir William Flower in his paper upon 

 the skull in the Carnivora showed that this animal is 

 really an ally of the Raccoons, which are purely an 

 American family. Everybody is acquainted with the 

 fact that monkeys are found both in the old world and in 

 the new. But the fact gets a far larger significance when 

 it is realised that the new world monkeys form a group 

 by themselves which differs from that of the old world 

 monkeys in a number of important anatomical characters. 

 The wide distance and the absence of means of transit 



