HYPOTRACHELIUM, in architecture, the space which lies between the annulets or little rings at the bottom of the echinus or convex portion of the Greek Doric capital, and the topmost stone of the column shaft proper. It is thus the lowest portion of the stone from which the capital is carved, and contains the tops of the column flutes. It is frequently decorated at the bottom by a groove or grooves circling the circumference, which may have inserted mouldings of bronze. The word is also sometimes ap plied in the Roman Doric order to the necking, or space between the bottom of the capital and the astragal, or convex moulding, with fillet below which marks the top of the shaft proper (see ORDER) .