See attached.  I welcome any suggestions on the style.  This would be the caption:

"(a) The spectrum from ZHS (dark gray), {symbol representing mine} (black), and Eq. 16 of ARVZ (light gray), scaled by R/E_C.  The cascade width for {symbol representing mine} is a=1.5 m, with R=1000m, F(omega) {not equal} 1 and LPM elongation (E_C = 100 TeV).  The thin black box at upper right encompases cases for which theta=theta_C, and the thin black box at lower left encompasses cases for which theta {not equal} theta_C.  The cases are (from right to left) theta_C - 2.5 deg, theta_C - 5.0 deg, theta_C - 7.5 deg, and theta_C - 10.0 deg. (b) ..."