Aporometridae HL Clark 1938

Aporometridae is a monotypic family of crinoids, the only genus being Aporometra, which contains three species, all endemic to the seas around Australia.

Small Notocrinoidea with centrodorsal low rounded to almost conical; aboral apex more or less flattened, rugose. Adoral side of centrodorsal with shallow radial pits. Aboral half of centrodorsal cavity filled with spongy stereom; no aboral pit or dorsal star. Cirrus sockets with indistinct sculpturing or with articular tubercles, but no marginal crenulae, in 10 columns of 1-4 sockets. Cirrals smooth, no aboral spines; distal cirrals flattened aborally-adorally. Rod-shaped basals exposed interradially or concealed. No subradial cleft. Radials with low exposed surface. Radial articular facet low and wide, angularly bent at fulcral ridge; low aboral ligament fossa almost parallel to oral-aboral axis; small interarticular ligament fossa and adoral muscle fossae almost at right angle to oral-aboral axis. Radial cavity moderate, without central plug. Syzygy between brachials 3-4 and 7-8 and distal generally at interval of 2. No distinct ambulacral covering plates, Viviparous; pinnules bear gonads and marsupia. Different larval stages carried in and on pinnules.