tectibranchiate

from The Collaborative International Dictionary of English v.0.48

Tectibranchiate \Tec`ti*bran"chi*ate\, a. [L. tectus (p. p. of
   tegere to cover) + E. branchiate.] (Zool.)
   Having the gills covered by the mantle; of or pertaining to
   the Tectibranchiata. -- n. A tectibranchiate mollusk.
   [1913 Webster]