Jordan and Evermann. Fishes of North America. 161 



auditus. Branchiostegals few, usually 3 or 4 ; shoulder girdle attached to 

 the skull. This group consists entirely of fresh-water fishes, and includes 

 about 8 families, to which belong the majority of all the fresh-water fishes 

 of the world. The essential character of the order lies in the modification 

 of the anterior vertebras, as in the NEMATOGNATHI, but without the 

 character of the rudimentary subopercle and maxillary and the scaleless 

 skin which distinguish the catfishes. Three strongly marked suborders 

 are included in it each of which has been sometimes regarded as a dis- 

 tinct order. There is no room for doubt that the EVENTOGNATHI and 

 HETEUOGNATHI, as well as the GYMNONOTI, sprang from the same stock 

 as the catfishes, as it is not likely that the singular modification of the 

 vertebra?, producing the Weberiau apparatus has separately developed 

 in the different groups. (7r?.e/crdf, woven together ; (m:6vdv?ioc, vertebra.) 



ANALYSIS OF SUBORDERS OF PLECTOSPONDYLI. 



a. Lower pharyngeals falciform, parallel with the gill arches; jaws toothless; brain case pro- 

 duced between orbits; basis cranii simple; only 2 superior pharyngeal bones. 



EVENTOGNATHI. 



aa. Lower pharyngeals not falciform; 3 basal branchihyals; teeth in jaws often present; 

 brain case not produced between orbits; basis cranii double, sometimes with muscular 

 canal; 1 to 4 superior pharyngeal bones. 

 6. Anus submedian; body not eel-shaped; dorsal fin present; ventrals abdominal. 



HETEROGNATHI. 



bb. Anus at throat; body elongate, more or less eel-shaped; dursal obsolete; ventrals want- 

 ing. GYMNONOTI. 



Suborder EVENTOGNATHI. 



(THE CARPS.) 



Plectospondylous fishes with the lower pharyngeals falciform, parallel 

 with the gill arches; 2 upper pharyngeal bones; brain case produced be- 

 tween orbits; jaws without teeth; dorsal fin present; no adipose fin; ven- 

 trals abdominal. Gill openings restricted, the gill membranes attached 

 to the isthmus. Streams and lakes of northern regions, the species ex- 

 cessively numerous. (ev, well; t-zrof, within; -yvuflos, jaw.) 



ANALYSIS OF FAMILIES OF EVENTOGNATHI. 



. Pharyngeal teeth numerous, pectinate; maxillaries forming part of the margin of the up- 

 per jaw; basal branchihyals 2. CATOSTOMID^:, xxxvi. 



aa. Pluiryngeal teeth few; margin of upper jaw formed by premaxillaries alone; basal 

 brauchihyals 3. CYPRINID.*:, xxxvu. 



Family XXXVI. CATOSTOMID^E. 



(THE SUCKERS.) 



Body oblong or elongate, usually more or less compressed. Head more 

 or less conical. Opercles normally developed. Nostrils double; no bar- 

 bels; mouth large or small, usually protractile and with fleshy lips. 

 Margin of upper jaw formed in the middle by the small premaxillaries, 

 and on the side by the maxillaries ; jaws toothless. Lower pharyngeal 

 bones falciform, armed with a single row of numerous comb-like teeth. 



F. N. A. - 12 



