The sixteen species of this group belong to the fauna of tropical America, and are referred to the genera Macrodon, Erythrinus, Lebiasina, Nannostomus, Pyrrhulina, and Corynopoma.
II. Curimatina.—A short dorsal and an adipose fin; dentition imperfect. Tropical America.
Curimatus.—Dorsal fin placed nearly in the middle of the body; anal rather short or of moderate length; ventrals below the dorsal. Body oblong or elevated, with the belly rounded or flattened before the ventrals. Cleft of the mouth transverse, lips none, margins of the jaws trenchant. No teeth whatever. Intestinal tract very long and narrow.
About twenty species are known, of rather small size.
The other genera of this group have teeth, but they are either rudimentary or absent in some part of the jaws: Prochilodus, Cænotropus, Hemiodus, Saccodon, Parodon.
III. Citharinina.—A rather long dorsal and an adipose fin; minute labial teeth. Tropical Africa.
One genus only, Citharinus, with two species, is known. Common in the Nile, attaining to a length of three feet.
IV. Anastomatina.—A short dorsal and an adipose fin; teeth in both jaws well developed; the gill-membranes grown to the isthmus; nasal openings remote from each other. Tropical America.
Leporinus.—Dorsal fin placed nearly in the middle of the length of the body; anal short; ventrals below the dorsal. Body oblong, covered with scales of moderate size; belly rounded. Cleft of the mouth small, with the lips well developed; teeth in the intermaxillary and mandible, few in number, flattened, with the apex more or less truncated, and not serrated; the middle pair of teeth is the longest in both jaws; palate toothless.
This genus is generally distributed in the rivers east of the Andes; about twenty species are known, some of which, like L. frederici, L. megalepis, are very common. They are well marked by black bands or spots, and rarely grow to a length of two feet, being generally much smaller.—The other genera belonging to this group are Anastomus and Rhytiodus.