276 CYPRINID.'E. 



tlie length of the snoiit, one-fourth of that of the postorhital'portion 

 of the head, and two-sevenths of the width of the interorbital space, 

 which is convex. PraBorbital nearly twice as long as deep, and 

 longer than the orbit ; the other suborbital bones narrow. Mouth 

 somewhat oblique, with the upper jaw scarcely overlapping the 

 lower, very broad ; bi^.t the maxillary terminates far in advance of 

 the orbit. Origin of the dorsal fin nearer to the root of the caudal 

 than to the end of the snout, a Little in advance of the origin of the 

 ventrals. Coloration uniform. 



California. 

 a, h, c. Adult (11-12 inches long). Paver San Joaquin. Presented 



by Dr. W. 0. Ayres. 

 J. Adult male : skeleton, lliver San .Joaquin. Presented by Dr. 



W. 0. Ayres. 

 The intestinal tract is very narrow, and about seven times as long- 

 as the entire fish. 



65. ACROCHILUS. 



Acrocheilus, Affossiz, Silliin. Journ. xix. 1855, p. 96. 



Scales ? Lateral line running along the median hue of the depth 

 of the tail. Dorsal fin short, with ten branched rays, inserted above 

 the root of the ventrals ; anal fin with about eleven rays ; caudal fin 

 remarlcahle for the many simple rays ivJiich it has along the hase of 

 its two lobes. Mouth inferior, transverse, lower jaw with a cutting 

 edge covered with a deciduous brown horny layer ; a similar trans- 

 verse bony plate along the inner edge of the intermaxillary bone. 

 Barbels none. Pharyngeal teeth 5 — 4. club-shaped, not denticu- 

 lated, terminating in a hook, with the inner (grinding) surface 

 obliquely cut. Peritoneum black. 



Columbia River. 



1 . AcrocMlus alutaceus. 



Acrocheilus alutaceus, Agass. i§- Pick. Sillim. Jouru. xix. 1855, p. 99. 

 No specific description has been given of this fish. 



Ninth Group. RHODEINA. 

 Anal fin of moderate length, with from nine to twelve branched 

 rays, extending forwards to below the dorsal. Dorsal fin short or 

 of moderate length. Lateral line, if complete, running along or 

 nearly in the middle of the tail. Mouth with very small, or with- 

 out any barbels. Pharyngeal teeth in a single series. 



66. ACHILOGNATHUS. 



Acheilognathus, Bleel-. Proch: Cypr. p. 228. 



Acheilognathus et Paracheilognathus, Bleek. Atl. Ichthyol. Cypr. p. 33. 



Scales of moderate size ; lateral line complete. Dorsal fin extend- 



