Types Ib and Ic are believed to correspond to stars ending their lives (as Type - II supernovae), but such stars would have lost their hydrogen before, and so hydrogen lines don't appear on their spectra (more discussion). (members.nova.org)
They have even weaker hydrogen lines than F, but along with the ionized metals, they have neutral metals. (en.wikipedia.org)
Types Ib and Ic are believed to correspond to stars ending their lives (as Type - II supernovae), but such stars would have lost their hydrogen before, and so hydrogen lines don't appear on their spectra (more). (members.nova.org)