(pl., rhachies) A pair of longitudinal ridges ventrally along the length of the fused second valvulae, which fit into the aulax of each first valvula to form the tongue-and-groove olistheter interlocking mechanism of the ovipositor stylets. [drawing

The continued stem or midrib of a pinnately compound leaf, as in a rose leaf or a fern.

The central cord in the stem of a crinoid.

A central cord of the ovary of nematodes.

The principal axis in a raceme, spike, panicle, or corymb.

The shaft of a feather. The rhachis of the after-shaft, or plumule, is called the hyporhachis.

see rachis.

The median part of the radula of a mollusk.

The spine.