142 OSTARIOPHYSI. 
Fam, 3. CYPRINIDA. 
Fresh-water fishes of North America, Eurasia, and Africa. The species are very 
numerous, about 1400 being known. The American Cyprinide extend southwards to 
the Rio Balsas in Southern Mexico and the Rio 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 3 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 pharyngeals are falciform, each with 1 to 3 series of teeth. 
Synopsis of the Genera represented in Mexico and Central America *. 
I. Mouth bordered above by the premaxillaries and the maxillaries; lips fleshy, papillose 
or plicated; pharyngeal teeth in a single series, 6 or more in number on each side. 
[ CaTostoMINa. | 
A. Dorsal fin long, of 20 to Si rays. . . . 2 e «© ee eh) OLS I eTrrosus. 
B. Dorsal fin short, of 8 to 16 rays. 
1. Body normally shaped; no nuchal hump. 
Scales moderate, 40 to 50 in a longitudinal series; jaws without carti- 
laginous sheaths . . .. . wee ew we ew ew ew ew ee 60. Moxostoma. 
Scales small, 60 to 100 in a longitudinal series ; jaws with more or less 
distinct cartilaginous sheaths . . . . . . 6... . . . 938, Carostomus, 
2. Nuchal region with an elevated sharp-edged hump, ¢ the inter- 
neural spines being enlarged and expanded; scales small . . 4. XyRaucHEN. 
II. Mouth bordered above by the premaxillaries ; lips not papillose nor plicated; pharyngeal 
teeth in 1 to 3 series, 3 to 6 in number in the main row on each side. [Cyprininz.] 
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 . . . . . . . . «es  ) . «66, CampPostoma. 
8. 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. 
+ Gill-rakers comparatively few and short. 
* A revision of the American Cyprinidz would probably show that several of the genera here recognized 
are untenable. For the present I have thought it best to agree as far as possible with the current American 
nomenclature for the fishes of this family. 
