VI PREFACE. 



(3) Winter Visitors, •\\hich visit us in winter^ but do not 

 breed here. 



(4) Occasional Visitors, ■vvliich are only of irregular occur- 

 reneOj but are met with in our islands with more or 

 less frequency. 



It is in many cases difficult to decide in which of these 

 four divisions a particular species should be placed ; but the 

 Table on the next page is believed to give with tolerable 

 accuracy the number of species^ in each of the seventeen 

 ordersj members of wliich occur in the British Isles. 



P. L. S. 



H. T. W. 



April 3rd, ISaS. 



