From book’s pattern description:

"The targets on these mittens were inspired by the look of traveling chemical waves.  Each mitten is worked flat with stripes in the rib and fingertips.  When working the hand, a semi-circle is left out where the thumb pad and thumb ought to be.  Later, stitches are picked up to create these missing parts and work the striking target motif simultaneously."

Pattern and photos can be found on pages 110-111 of Interweave Knits, Fall 2006.