石燕贝属
Spirifer \Spi"ri*fer\, n. [NL., fr. L. spira a coil + ferreto bear.] (Paleon.) Any one of numerous species of fossil brachipods of the genus {Spirifer}, or {Delthyris}, and allied genera, in which the long calcareous supports of the arms form a large spiral, or helix, on each side.