PREFACE. Vll 



my friend John Gray, Esq., having liberally offered to take 

 me, in his yacht 'the Miranda/ on a cruise amongst the 

 islands of that Group. Mr. Gray being equally anxious with 

 myself to investigate the fauna, I felt that this proposal 

 (which included likewise his valuable assistance in matters 

 entomological) was not to be rejected; and accordingly in 

 January of 1858 we reached our destination, and, after being 

 joined by the Rev. R. T. Lowe (who was passing the winter in 

 Teneriffe), began our researches in the Canarian archipelago, 

 visiting the different parts of it in rotation. Although 

 Mr. Gray's continuance with us was cut short by his desire 

 to cross the Atlantic on his homeward route, I nevertheless 

 remained in the Canaries until the following July; and, 

 having become much interested in the result of a six-months' 

 toil, I again left England, at the close of 1858, and spent 

 from February to July of 1859 amongst the same islands 

 principally, as before, in company with Mr. Lowe. 



Or. my return home in the summer of 1859, I commenced 

 the almost hopeless operation of throwing into systematic 

 order, and examining critically, every single specimen (some 

 20,000, at the very least) which I had accumulated during 

 these two Canarian campaigns, as well as those which were 

 amassed by Mr. Gray at the beginning of our first trip ; and 

 I had likewise the advantage of a few smaller collections, and 

 types, communicated by Dr. Heer, M. Hartung, the Barao 

 do Castello de Paiva, MM. Chevrolafc, Schaum, Deyrolle, &c., 

 from the continent. Yet, in spite of this vast amount of 

 combined material, I found that there were some wide gaps 

 in the local distribution of the several forms, owing to 

 certain islands, particularly Gomera, having been visited by 

 us in comparative haste, and during the depth of winter; 

 and it seemed, therefore, well nigh presumptuous to attempt 



