primibrach

from The Century Dictionary.

• noun In Bather's terminology of crinoid morphology, one of the ossicles (primibrachialia) of a pinnulate dichotomous arm situated between the upper margins of the radials and below the first axillaries, which by other writers have been called radials of the first order, and costals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A brachial on the unbranched arm of a crinoid