The Collaborative International Dictionary of English v.0.48:
Reptantia \Rep*tan"ti*a\ (r?p-t?n"sh?-?), n. pl. [NL.] (Zool.) A division of gastropods; the Pectinibranchiata. [1913 Webster]WordNet (r) 3.0 (2006):
Reptantia n 1: lobsters; crabs [syn: Reptantia, suborder Reptantia]