The buffalo-fishes and carp-suckers, constituting the genera Ictiobus and Carpiodes, are the largest of the Catostomidæ, and bear a considerable resemblance to the carp. They have the dorsal fin many rayed and the scales large and coarse. They abound in the large rivers and lakes between the Rocky Mountains and the Alleghanies, one species being found in Central America and a species of a closely related genus (Myxocyprinus asiaticus) being reported from eastern Asia. They rarely ascend the smaller rivers except for the purpose of spawning. Although so abundant in the Mississippi Valley as to be of importance commercially, they are very inferior as food-fishes, being coarse and bony. The genus Cycleptus contains the black-horse, or Missouri sucker, a peculiar species with a small head, elongate body, and jet-black coloration, which comes up the smaller rivers tributary to the Mississippi and Ohio in large numbers in the spring. Most of the other suckers belong to the genera Catostomus and Moxostoma, the latter with the large-toothed Placopharynx being known, from the red color of the fins, as red-horse, the former as sucker. Some of the species are very widely distributed, two of them (Catostomus commersoni, Erimyzon sucetta) being found in almost every stream east of the Rocky Mountains and Catostomus catostomus throughout Canada to the Arctic Sea. The most peculiar of the suckers in appearance is the harelip sucker (Quassilabia lacera) of the Western rivers. Very singular in form is the humpback or razor-back sucker of the Colorado, Xyrauchen cypho.
Fig. 137.—Common Sucker, Catostomus commersoni (Le Sueur). Ecorse, Mich.
Fig. 138.—California Sucker, Catostomus occidentalis Agassiz. (Photograph by Cloudsley Rutter.)
Fossil Cyprinidæ.—Fossil Cyprinidæ, closely related to existing forms, are found in abundance in fresh-water deposits of the Tertiary, but rarely if ever earlier than the Miocene. Cyprinus priscus occurs in the Miocene of Germany, perhaps showing that Germany was the original home of the so-called "German carp," afterwards actually imported to Germany from China. Some specimens referred to Barbus, Tinca, Rhodeus, Aspius, and Gobio are found in regions now inhabited by these genera, and many species are referred to the great genus Leuciscus, Leuciscus œningensis from the Miocene of Germany being perhaps the best known. Several species of Leuciscus or related genera are found in the Rocky Mountain region. Among these is the recently described Leuciscus turneri.
Fig. 139.—Pharyngeal teeth of Oregon Sucker, Catostomus macrocheilus.
Fossil Catostomidæ are very few and chiefly referred to the genus Amyzon, supposed to be allied to Erimyzon, but with a longer dorsal. Amyzon commune and other species are found in the Rocky Mountains, especially in the Miocene of the South Park in Colorado and the Eocene of Wyoming. Two or three species of Catostomus, known by their skulls, are found in the Pliocene of Idaho.
