The Collaborative International Dictionary of English v.0.48:

Saxicava \Sax`i*ca"va\, n.; pl. E. saxicavas, L. Saxicavae.
   [NL. See Saxicavous.] (Zool.)
   Any species of marine bivalve shells of the genus Saxicava.
   Some of the species are noted for their power of boring holes
   in limestone and similar rocks.
   [1913 Webster]