Fig. 125.—Silver-jaw Minnow, Ericymba buccata Cope. Defiance, Ohio.
In America 225 species of Cyprinidæ are known. One hundred of these are now usually held to form the single genus Notropis. This includes the smaller and weaker species, from two to seven inches in length, characterized by the loss, mostly through degeneration, of special peculiarities of mouth, fins, and teeth. These have no barbels and never more than four teeth in the main row. Few, if any, Asiatic species have so small a number, and in most of these the maxillary still retains its rudimentary barbel. But one American genus (Orthodon) has more than five teeth in the main row and none have more than two rows or more than two teeth in the lower row. By these and other peculiarities it would seem that the American species are at once less primitive and less complex than the Old World forms. There is some evidence that the group is derived from Asia through western America, the Pacific Coast forms being much nearer the Old World types than the forms inhabiting the Mississippi Valley. Not many Cyprinidæ are found in Mexico, none in Cuba, South America, Australia, Africa, or the islands to the eastward of Borneo. Many species are very widely distributed, many others extremely local. In the genus Notropis, each river basin in the Southern States has its series of different and mostly highly colored species. The presence of Notropis niveus in the Neuse, Notropis pyrrhomelas in the Santee, Notropis zonistius in the Chattahoochee, Notropis callistius, trichroistius, and stigmaturus in the Alabama, Notropis whipplei in the Mississippi, Notropis galacturus in the Tennessee, and Notropis cercostigma in the Sabine forms an instructive series in this regard. These fishes and the darters (Etheostominæ) are, among American fishes, the groups best suited for the study of local problems in distribution.
Fig. 126.—Silverfin, Notropis whipplei (Girard). White River, Indiana. Family Cyprinidæ.
Species of Dace and Shiner.—Noteworthy species in other genera are the following:
Largest and best known of the species of Notropis is the familiar shiner or redfin, Notropis cornutus, found in almost every brook throughout the region east of the Missouri River.
Campostoma anomalum, the stone-roller, has the very long intestines six times the length of its body, arranged in fifteen coils around the air-bladder. This species feeds on mud and spawns in little brooks, swarming in early spring throughout the Mississippi Valley, and is notable for its nuptial tubercles and the black and orange fins.
Fig. 127.—Stone-roller, Campostoma anomalum (Rafinesque). Family Cyprinidæ. Showing nuptial tubercles and intestines coiled about the air-bladder.