A genus unfigured and imperfectly described as differing in some respects from Terebratula and other brachiopod.
The process is apparently the same in a nebula or a brachiopod, although much more intricate in the latter.
Spirifer, spir′i-fėr, n. a brachiopod of the Carboniferous system.
Any of various marine invertebrate animals of the phylum Brachiopoda that resemble clams. Brachiopods have paired upper and lower shells attached to a usually stationary stalk and hollow tentacles covered with cilia that sweep food particles into the mouth. Brachiopods are probably related to the phoronids and bryozoans, and were extremely abundant throughout the Paleozoic Era.