2 YORKSHIRE NATURALISTS UNION. 



3. North West. — The hill-districts of the North and West 



Ridings as far south as Keighley and Rombald's 

 Moors, and such portion of the Vale of Mowbray as 

 lies west of the rivers Wiske and Swale. 



4. Central. — The great central plain of the county or Vale 



of York ; defined for convenience sake by the railway 

 lines from Arthington to Boroughbridge, Malton, and 

 Wharram Percy, on the east by the western escarpment 

 of the Wolds, and on the south by the rivers Aire and 

 Ouse. 



5. South West. — The southern portion of the West Riding. 



I have to tender my best thanks to Mr. Wm. Denison 

 Roebuck for a vast amount of material, carefully and 

 methodically amassed ; to Mr. E. B. Wrigglesworth, for the use 

 of a large number of MS. notes, invaluable for the south-western 

 portion of the county ; to Mr. Lawson, of Scarborough, for 

 similar help in regard to the wonderfully rich entomological 

 fauna of that neighbourhood ; and to the Rev. W. W. Fowler for 

 much useful assistance, especially in the identification of obscure 

 species. In conclusion I have to crave the indulgence to which 

 the difficulty of the work may perhaps give me some claim. 



The initials of authorities have been used for the sake of 

 brevity in the following cases : — 



Trans. Y.N. U., ISS5 (pub. lS-<6). Series D. Vol. 3. 



