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Final Report endangered species in 1980. The occurrence of this species in Grand Canyon is based on 16 specimens reported by RR Miller in the 1940s (M. Douglas, ASU, pers. comm.) Bonytail have an elongated fusifonn body, small flattened head with small eyes, subtenninal mouth, long slender caudal peduncle, and large deeply forked tail fin. Subadults are olivaceous above with silvery sides fading to a creamy white belly, while adults are greenish to gray dorsally and laterally, with a white belly and irregular black lateral spots. Dorsal and anal fins typically have 10 principal rays each; caudal peduncle length divided by head length is typically greater than 1.0, and head length divided by caudal peduncle depth is usually greater than 5. O. Scales are small dorsally and ventrally, larger laterally, and embedded throughout with 75-88 sCales along the lateral line. The pharyngeal arch is smal1 with a short lower ramus and deciduous teeth in a typical pattern of 2,4-5,2. Roundtail Chub (Gila robusta) The roundtail chub is locally common in middle to upper elevations of the mainstem and tributaries of Prologue . xxiii the Colorado River. It is not federally protected, but is of special concern in all seven basin states. Its occwrence in Grand Canyon is based on reports by McDonald and Dotson (1960) and Stone and Rathbun (1968). Although roundtail chub have not been reported from the Colorado River in Grand Canyon since 1968, the species was recently reported from Chevlon Creek, a tributary of the LCR in Arizona (R Clarkson, AGF, pers. comm.) Roundtail chub have a cylindrical body and head, with small eyes, and a terminal mouth, short thickened caudal peduncle, and rounded tail fin and paired fins. Subadults are olivaceous above with silvery sides fading to a creamy white belly, while adults are olivaceous dorsally and laterally, with a white belly and irregular black lateral blotches. Dorsal and anal fins typically have 9 and 9 principal rays, respectively; caudal peduncle length divided by head length is typically less than 1.0, and head length divided by caudal peduncle depth is usually less than 4.0. Scales are small dorsally and ventrally, larger laterally, and imbricated throughout with 75-96 along the lateral line. The pharyngeal arch is small with a short lower ramus and deciduous teeth in a typical pattern of2,4-5,2. Roundtail chub