crossopterygia

from The Century Dictionary.

• In Cope's early system of classification, a subclass of fishes.
• In Cope's later system (1887), a superorder limited to teleostomous fishes having dorsal, anal, pectoral, and ventral basilar segments for the fins, those of the dorsal and anal numerous and each articulating with a single element, if any, and the actinosts numerous in the pectorals and ventrals.
• Plural of crossopterygium.