The Echinoid Directory

Glossary

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Glossary terms beginning with: N

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neck
In spines, a zone at the base of the shaft that lacks a cortex covering
neck
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. (show image)
notch
An ovate to slit-like indentation at the margin of the test positioned at an interradial, adradial or perradial plate-plate boundary. (show image)