What is "dibranchiata"

Dibranchiata \Di*bran`chi*a"ta\, n. pl. [NL., fr. Gr. di- = di`s- twice + ? gills.] (Zo["o]l.) An order of cephalopods which includes those with two gills, an apparatus for emitting an inky fluid, and either eight or ten cephalic arms bearing suckers or hooks, as the octopi and squids. See Cephalopoda.