142 OSTAEIOPllTSI. 



Fam. 3. CYPKINID^. 



Fresh-water fishes of North America, Eurasia, and Africa. The species are very 

 numerous, about 1-100 being l-cnown. Tlie American Cypriniclas extend soutliwards to 

 the Eio Balsas in Southern Mexico and the Eio Usumacinta in Guatemala. The 

 Mexican and Central-American representatives are scaly fishes, with the mouth 

 toothless, with the gill-membranes joined to the isthmus and with o branchiostegals. 

 There are no spinous fin-rays, the single dorsal fin is not followed by an adipose fin 

 and the ventral fins are abdominal, 7- to 12 -rayed. The upper pharyngeals are 

 toothless and the lower pliarj-ngeals are falciform, each with 1 to 3 series of teeth. 



Synopsis of flic Genera represented in Mescico and Centred America''-. 



I. ]\Ioutli bordered above by tlie prieniaxillaries and the maxillarlcs ; lips fleshy, papillose 

 or pHcated; pharyngeal teeth in a single series^ 6 or more in number on each side. 

 [Catostomin.e.] 



A. Dorsal fin long, o£ 20 to 35 rays 1. Ictiobus. 



B. Dorsal fin short, of 8 to IG rays. 



1. Body normally shaped ; no iiuehal hump. 



Scales moderate, 40 to 50 in a longitudinal series; jaws without carti- 

 laginous sheaths 2. IMoxostoma. 



Scales small, GO to 100 in a ]ongitudi)uil series ; jaws with more or less 



distinct cartilaginous sheaths .3. Catostomus. 



2. Nuchal region with an elevated sharp-edged hump, the inter- 



neural spiucs being enlarged and expanded ; scales small . . 4. Xyrauciien. 



11. Mouth bordered above by the prtemaxillarics ; lips not papillose nor plicated ; pharyngeal 

 teeth in 1 to 3 series, 3 to 6 in number in the main row on each side. [Cypkinin.e.] 

 A. No barbels. 



1. Abdomen behind the ventral fins compressed to form a keel ; 



anal fin more or less elongate 5. Abramis. 



2. Abdomen not compressed to an edge. 



a. Anterior 2 or 3 rays of dorsal fin simple, graduated and closely connected, the first 

 not enlarged nor separated by a membrane from the second. 

 a. Air-bladder completely surrounded by convolutions of the 



very long intestine 6. Campostoma. 



/3. Air-bladder not surrounded by the intestine. 



* Pharyngeal teeth subconical or more or less compressed and hooked, 4 to 6 in 

 the main row on each side, 

 t Gill-ra]<crs comjiarativcly few and short. 



* A revision of the Aroerican Cyprinidio would probably show that several of the genera here recognized 

 are untenable. For the present I have thouglit it best to agree as far as possible with the current Americau 

 nomenclature for the fishes of this family. 



