PREFACE. 



The Introduction to this edition contains, 1st, an 

 explanation of the means which I have used to 

 improve the work ; 2dly, an account of the species 

 which I have reason to believe had been, from various 

 causes, erroneously introduced into w r orks of this 

 kind, and the grounds on which they have been 

 here rejected; 3dly, a sketch of the geographical dis- 

 tribution of the species, as compared with the rest of 

 the world, and with different parts of our own country. 

 I fear that this part of the subject, which has been 

 here taken up for the first time, from the poverty of 

 the materials at my disposal, is not so perfect as it 

 should be ; but it is to be hoped, that readers living 

 in different parts of the country (now that their 

 observation is directed to the subject) will pay more 

 attention to it, so that in future editions of the work 

 it may be carried out in a more complete manner. It 

 should be observed, that the whole value of the lists, and 

 of the table, must depend on the accurate determin- 

 ation of the species, which is of the first importance ; 

 while the extent of the list (which appears to be 

 the general pride of the local collector) is of a very 

 secondary consideration. Since this part of the work 

 was printed, Mr. Forbes has presented to the British 

 a 3 



