• (a.) Pertaining to the Physostomi. • (a.) Having a duct to the air bladder.
Phy·sos'to·mous adjective (Zoology) (a) Having a duct to the air bladder. (b) Pertaining to the Physostomi. 
physostome, physostomi, physostomatous, physostomous Fish that have a pneumatic duct leading from the air bladder to some part of the alimentary canal (usually the esophagus); they include members of a number of suborders and the name is no longer used in systematic classification. —A Dictionary of Zoology by A. W. Leftwich (London: Constabl...