| Noun | 1. | subclass Dipnoi - bony fishes of the southern hemisphere that breathe by a modified air bladder as well as gills; sometimes classified as an order of Crossopterygiiclass Osteichthyes, Osteichthyes - a class of fish having a skeleton composed of bone in addition to cartilage lungfish - air-breathing fish having an elongated body and fleshy paired fins; certain species construct mucus-lined mud coverings in which to survive drought Ceratodontidae, family Ceratodontidae - lungfishes having hornlike ridges on the teeth class - (biology) a taxonomic group containing one or more orders |