INTRODUCTION. 55 



been very different. The one has left a favorable record 

 of liimself throughout ; -vvhilc of the other, only traces 

 enough rem am, to mark his errors. 



The other principal contributors to the elucidation of 

 this branch of zoology mil be named in the general 

 remarks on the respective genera, and a particular 

 account of their contributions to the history of the genus 

 will be given. 



