Source : Webster's Revised Unabridged Dictionary (1913)

Leptostraca \Lep*tos"tra*ca\ (l[e^]p*t[o^]s"tr[.a]*k[.a]), n.
   pl. [NL., fr. Gr. lepto`s thin, slender + 'o`strakon shell of
   a testacean.] (Zo["o]l.)
   An order of Crustacea, including Nebalia and allied forms.