from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of or pertaining to the hypotheca, the lower half of the shell of certain types of plankton
from The Century Dictionary and Cyclopedia
- Situated beneath or within the test, as the radial water-tubes of echinoids. Compare epithecal, 2.
- Of or pertaining to the hypotheca of a diatom.
hypotheca + -al (Wiktionary)