The genera are:—Protopterus (1 sp.), Tropical Africa; Lepidosiren (1 sp.), Amazon Valley; Ceratodus (1 sp.), Queensland.
Sub-class III.—GANOIDEI.
Order I.—HOLOSTEI.
"Body covered with scales."
Family 93.—AMIIDÆ. (1 Genus, 1 Species.)
"A fresh-water fish, with cycloid scales and a long soft dorsal fin."
Distribution.—United States.
Family 94.—POLYPTERIDÆ. (2 Genera, 2 Species.)
"Fresh-water fishes, with ganoid scales and dorsal spines."
Distribution.—Central and Western Africa.