98 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY III 



Early writers on fishes, as well as most foreign ichthyologists, have 

 considered the Suckers as forming a mere tribe or subfamily of the 

 Cyprinidce, which group has been variously denominated Catostomi, 

 Catostomina, and Catcstomince, but the characters above noted, of teeth 

 and mouth, seem to the writer to fully justify their separation as a dis- 

 tinct family TVa dorsal fin in Catostomidce is more developed than is 

 usual in American C^prinidce, although various Old World genera show 

 similar characters. The development of the lips and the great protrac- 

 tility of the mouth are features usually diagnostic, but in the genus 

 Quassi'abia the mouth is scarcely piotractile, and among our Cypri- 

 nidce certain species of Phenaeobius and Ceratichthys have thicker lips 

 than have some of the Catostomidce. 



The Catostomidce fall at once into three well-marked subfamilies, first 

 indicated by Professor Gill, and termed by him Catostomince, Cycleptince, 

 and Bubalichthyincc. These may be characterized as follows: 



Catostomince. Body oblong or elongatjp, subterete or more or less 

 compressed : dorsal fin nearly median, short and subquadrate, with 

 from nine to eighteen developed rays: ventral fins under the dorsal, of 

 nine or ten rays : anal fin high and short, normally of seven rays, nearer 

 the base of the caudal than that of the ventral fins : lips well developed, 

 usually papillose or plicate : gill-rakers little developed. Genera Quassi- 

 labia, Placopharynx, Myxostoma, Erimyzon, Minytrema, Chasmistes, 

 Catostomus, Pantosteus. 



Cycleptince. Body elongate, slender : dorsal fin falciform, of about 30 

 rays, beginning over the interval between the pectoral and ventral fins, 

 and extending as far back as the beginning of the anal fin : ventral fins 

 10 rayed; anal fin small, of about 7 rays: head extremely small: scales 

 moderate, with the exposed surfaces broad : fontauelle entirely obliter- 



times absent; the head is diversiform ; the opercular bones normally developed ; the 

 nostrils double ; the mouth more or less inferior, and provided with fleshy and gener- 

 ally papillose or crenated lips ; the upper jaw is formed on the middle by the small 

 and lamelliform intermaxillaries, and on the sides by the supramaxillaries ; teeth are 

 wanting in the jaw j; the pharyngeal bones are developed in a falciform manner, and 

 provided with a row of numerous comb-like teeth ; the branchial apertures are re- 

 stricted to the sides ; branchiostegal rays three on each side ; dorsal variable in devel- 

 opment ; anal posterior, and generally short and high ; caudal large, and more or less 

 emarginated; pectoral fins low down, but lateral and with their rays branched; ven- 

 tral fins abdominal ; the intestinal canal is very long ; the stomach simple and desti- 

 .tute of pyloric caeca ; the air-bladder is large, unprotected by an osseous capsule, and 

 divided by transverse constrictions into two or three regions." 



