270 fYPRINin.K, 



the length of the snout, one-fourth of that of the postorbital portion 

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

 which is convex. Prajorbital 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 ; but 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 unifonu. 



California. 

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



by Dr. W. 0. Ayres. 

 (/. Adult male : skeleton. River 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, Agassiz, Sillim. Journ. xix. 1855, p. 96. 



Scales ? Lateral line running along the median line 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 

 remarKahle for the many simple rays ivhich it has along the base 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. Acrochilus alutaceus. 



Acrocheilus alutaceus, Ayass. ^- Pick. Sillim. Journ. 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. 



0.6. ACHILOGNATHUS. 



Acheilognathus, Bleeh. Prodr. Cypr. p. 228. 



Achoilognathus ct Paracheilognathiis, Blcck.Atl.Ichthyol. Cypr. p. 33. 



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



