From The Collaborative International Dictionary of English v.0.48 [gcide]:
Dibranchiata \Di*bran`chi*a"ta\, n. pl. [NL., fr. Gr. di- =
di`s- twice + ? gills.] (Zool.)
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.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
Dibranchiata
n 1: comprising all living cephalopods except the family
Nautilidae: the orders Octopoda (octopuses) and Decapoda
(squids and cuttlefish) [syn: Dibranchiata, {subclass
Dibranchiata}, Dibranchia, subclass Dibranchia]