QCD with eight flavors is studied on 1 6~ x Nt lattices with Nt = 4, 6 , 8, 16, and 32, a dynamical quark mass m a = 0.015, and lattice coupling P = 6/g2 between 4.5 and 5.0. For Nt = 16 and 32, hadron masses and screening lengths are computed for a variety of valence quark masses. The previously observed, strong, first-order transition for Nt = 4, 6, and 8 is seen, for Nt = 16, to become a P-independent, zero-temperature transition characterized by a factor of G 3 change in lattice scale. This strong, first-order transition restores chiral symmetry, at least for Nt = 4, 6, and 8, producing a chirally symmetric, weak-coupling phase. However, as Nt increases to 16, the chiral-symmetry properties of the weak-coupling side of the zero-temperature transition are unclear and offer a hint of a normal, finite-temperature, chiral-symmetry-breaking transition in the weak-coupling phase. PACS number(s): 12.38.Gc, 11.15.HaThis behavior is described by the phase structure in the P-Nt plane shown in Fig. 1. (The figure depicts a lattice of infinite spatial extent.) The solid line represents the strong, first-order transition, which varies with Nt for Nt < 8 and becomes a zerc-temperature or bulk transition for Nt > 8. The dashed line expresses our 5 5655