Glossary terms beginning with: N
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In spines, a zone at the base of the shaft that lacks a cortex covering
- neural notch
A notch than indents an ambulacral pore or pore-pair (the more perraidal of a pair) and which houses a side-branch from the radial nerve.
An ovate to slit-like indentation at the margin of the test positioned at an interradial, adradial or perradial plate-plate boundary.