Fig. 133.—Lower pharyngeal of Placopharynx duquesnii (Le Sueur).
The Catostomidæ.—The suckers, or Catostomidæ, are an offshoot from the Cyprinidæ, differing chiefly in the structure of the mouth and of the lower pharyngeal bones. The border of the mouth above is formed mesially by the small premaxillaries and laterally by the maxillaries. The teeth of the lower pharyngeals are small and very numerous, arranged in one series like the teeth of a comb. The lips are usually thick and fleshy, and the dorsal fin is more or less elongate (its rays eleven to fifty in number), characters which distinguish the suckers from the American Cyprinidæ generally, but not from those of the Old World.
About sixty species of suckers are known, all of them found in the rivers of North America except two, which have been recorded on rather uncertain authority from Siberia and China. Only two or three of the species extend their range south of the Tropic of Cancer into Mexico or Central America, and none occur in Cuba nor in any of the neighboring islands. The majority of the genera are restricted to the region east of the Rocky Mountains, although species of Catostomus, Chasmistes, Deltistes, Xyrauchen, and Pantosteus are found in abundance in the Great Basin and the Pacific slope.
Fig. 134.—Creekfish or Chub-sucker, Erimyzon sucetta (Lacépède). Nipisink Lake, Illinois. Family Catostomidæ.
In size the suckers range from six inches in length to about three feet. As food-fishes they are held in low esteem, the flesh of all being flavorless and excessively full of small bones. Most of them are sluggish fishes; they inhabit all sorts of streams, lakes, and ponds, but even when in mountain brooks they gather in the eddies and places of greatest depth and least current. They feed on insects and small aquatic animals, and also on mud, taking in their food by suction. They are not very tenacious of life. Most of the species swarm in the spring in shallow waters. In the spawning season they migrate up smaller streams than those otherwise inhabited by them. The large species move from the large rivers into smaller ones; the small brook species go into smaller brooks. In some cases the males in spring develop black or red pigment on the body or fins, and in many cases tubercles similar to those found in the Cyprinidæ appear on the head, body, and anal and caudal fins.
Fig. 135.—Buffalo-fish, Ictiobus cyprinella (Cuv. & Val.). Normal, Ill.
Fig. 136.—Carp-sucker, Carpiodes cyprinus (Le Sueur). Havre de Grace.