physophorae

from The Century Dictionary.

• noun An order of siphonophorous oceanic hydrozoans, having the proximal end modified into a float or pneumatophore (as distinguished from a somatocyst).

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) An order of Siphonophora, furnished with an air sac, or float, and a series of nectocalyces. See Illust. under nectocalyx.