The triatomic hydrogen ion (H + 3 ) has spurred tremendous interest in astrophysics in recent decades, and Rydberg states of H 3 have also maintained an important role for understanding H + 3 experiments. In a previous study [J. Chem. Phys. 133, 234302 (2010)], radiative transitions between neutral H 3 Rydberg states were calculated at wavelengths near 7 microns, andcould be compared with mid-infrared laser lines observed in hydrogen/rare gas discharges. The present study extends the investigation to wavelengths near 10 -13 microns. Rydberg states of D 3 are also treated.