Treated as plural. A former order of barnacles which bore into a variety of calcareous material, comprising typically small, shell-less forms having several pairs of cirri towards the end of the thorax.
((n. pl.) A group of cirripeds having abdominal appendages.)
Origin:
Mid 19th century; earliest use found in Charles Darwin (1809–1882), naturalist, geologist, and originator of the theory of natural selection. From scientific Latin Abdominalia from post-classical Latin abdominalis + -ia.