The Collaborative International Dictionary of English v.0.48:

Halysites \Hal`y*si"tes\ (h[a^]l`[i^]*s[imac]"t[=e]z), n. [NL.,
   fr. Gr. "a`lysis a chain.] (Paleon.)
   A genus of Silurian fossil corals; the chain corals. See
   Chain coral, under Chain.
   [1913 Webster]