Allan,
Like I said, you have Vol. 2 of the little 2 volume set. The black covered one is 60 pages and is the one I am most interested in.
I have found the 2 volume set at a reasonable cost.
This is the bookseller's description of the little 2 vol. set:
Book Description: 2-volume set; Text volume in black paper covers; 12mo; 60pp; illustrated with drawings, photos & charts. Second volume spiral comb style binding with plastic overleaf protector; 12mo; 20pp; illustrated with color photos and drawings. Details on 10 major mayfly types with color photos of nymph, male dun, female dun and spinners and the corresponding flies to imitate them. The text volume tells the life cycle of the mayfly; seasons of emergence with detailed tying instructions for various mayfly patterns. Getting hard-to-find as most of these booklets were placed in a fishing vest pocket. This set good to very good with moderate wear and rear corner of text volume clipped.