Jordan and Evermann. — Fishes of North America. 173 



92. CATOSTOMUS. Le Sueur. 

 (Fine-scaled Suckers.) 



Vtiloslomiis, Le Sueur, Jour. Ac. Nat. Sci. Phila., 1,1817,89, (catosloimis). 



Hiipenlrliniii, Rafinesque, Jour. Ac. Nat. Sci. Philu., 181S, 421, (nuwroplermn^nigricans). 



Etmjslomus, Bafi.vesque, Ich. Oh., 59, 1820, [nmjaslomus, based on an incurred drawing). 



Decadijbts, Rafinesque, Ich. Oh., GO, 1820, {hosloniensis = commersouii). 



Jlijlomyzon, Agassiz, Am. Jour. Sci. Arts, 1855, 205, (nigricans). 



Miiiomiis, GiRAUD, Proc. Ac. Nat. Sci. Phila., 1856, 1T3, (insignis). 



Acomiis, GiRARD, Z. c, 173, 1850, (/ors/eWaiiHs). 



Head, more or less elongate ; eye rather small, high up : suborbital bones 

 narrow, fontauelle always present, widely open. Mouth rather large, 

 always inferior, upper lip thick, protractile, papillose ; lower lip greatly 

 developed, with a broad free margin, usually deeply incised behind, so 

 that it forms 2 lobes which are often more or less separated. Mandible 

 horizontal, short, not i the length of the head and not reaching to oppo- 

 site the eye. Opercles moderate. Pharyngeal bones moderate ; the teeth 

 shortish, vertically compressed, rapidly diminishing in size upward. 

 Bodj^ elongate, more or less fusiform, subterete. Scales comparatively 

 small, typically much smaller and crowded anteriorly, the number in the 

 lateral line from 50 to 11.5, the number in a transverse series between 

 dorsal and ventrals from 15 to 40. Lateral line well develojied, straightish. 

 Dorsal with its first ray nearly midway of the body, with from 9 to 14 

 developed rays. Anal fin short and high, with 7 developed rays ; ventrals 

 inserted under the middle or posterior part of the dorsal, with 9 or 10 

 rays ; caudal fin forked, the lobes nearly equal. Sexual peculiarities not 

 much marked ; the fins higher in the male and the anal somewhat swollen 

 and tuberculate in the spring. Breeding males in most species with a 

 rosy or orange lateral band. Air bladder with 2 chambers, the poste- 

 rior chamber large. Vertebraj 45 to 47. Species very numerous, all 

 belonging to the United States, except the Siberian C. rostratiis Tilesius. 

 Many of the western species are imperfectly known, and the following 

 key is far from complete, {kcito), inferior; aTo/m, mouth.) 



:t. Head transversely convex above, the orbital rim not elevated; scales in lateral line GO or 

 more. 

 Catostomus : 

 b. Scales very small, much reduced and crowded anteriorly, the number in the lateral 

 line 80 tolls. 

 0. Ujiper lip very broad, with .several (5 or G) rows of paiiilla\ 



d. Dorsal fin of 11 to J3 rays, very high, especially in the male, the free edge of 



dorsal deeply incised; caudal very strong; the rudimentary rays at its base 

 largely developed in the adult, the caudal peduncle slender; these charac- 

 ters all most strongly marked in adult males; lips very full. 



I.ATtPlNNIS, 279. 



dd. Dorsal fin of 10 to 12 rays, moderately developed; caudal fin moderate, it-« 



rudimentary rays few, the peduncle rather stout; lii)sfull; lower lipsplit 



to base. qriseus, 280. 



cc. Upper lip thick but narrow, with 3 rows of papilla;. D. 9 or 10. pocateli.o, 2.S1. 



ccc. Upper lip comparatively thin and narrow with 2 to 4 rows of papillae; dorsal rays 



10 or 11. 



e. Scales in lateral line \K) to 115; body slender, the head long-conical; month 



narrow, lower lip split to base, but the lobes short. catostomus, 282. 



ee. Scales in lateral line 83 to 87; body and head stouter. tahoensis, 283. 



eee. Scales in lateral line 80; lower jaw strong. bex, 284. 



