AGOSIA.—RHINICHTHYS, 165 
22. AGOSIA, Girard, 1856. 
Ayosia, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 308. 
Differs from Hydopsis in the smaller scales, 60 to 90 in a longitudinal series, and in the more posterior 
position of the dorsal fin, which is often partly above the anal. 
About ten species, small fishes of the mountain streams of Western North America, 
two of which have been recorded from Northern Mexico. 
1. Agosia oscula. 
Aryyreus osculus, Girard, Proc. Ac, Philad. 1856, p. 186', and U.S. Mex. Bound. Surv., Fish. p. 47, 
t. 27. figs. 9-12 (1859) °*. 
Argyreus notabilis, Girard, |. c.*, and t. c. p. 47, t. 27. figs. 5-8 *. 
Agosia oscula, Jord. & Everm. Bull. U.S, Nat. Mus. xlvii. 1896, p. 309°; Meek, Publ. Columbian 
Mus., Zool. v. 1904, p. 80°. 
Hab. Gila River in Arizona: 
Recorded in Mexico from the Rio Santa Cruz ?4 in Northern Sonora, a tributary 
of the Gila. 
2. Agosia chrysogaster. 
Agosia chrysogaster, Girard, Proc. Ac. Philad. 1856, p. 187*, and U.S. & Mex. Bound. Surv., Fish. 
p. 49, t. 28. figs. 5~8 (1859)°; Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 313° ; 
Meek, Publ. Columbian Mus., Zool. v. 1904, p. 80°. 
Hab. Gila River in Arizona; Sonora and Western Chihuahua : 
Rio Santa Cruz!2, Hermosillo* and Rucker Cafion* in Sonora; Sierra Madre 
in Chihuahua 4, 
98. RHINICHTHYS, Agass., 1850. 
Rhinichthys, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 305. 
Body elongate, little compressed. Mouth non-protractile, subterminal or inferior; a small barbel at the end 
of each maxillary. Pharyngeal teeth compressed, hooked, in two series, 2, 4—4,2or1. Gill-openings 
separated by a broad isthmus. Scales small. Dorsal and anal fins short, the former about in the 
middle of the length of the fish; ventral fins 7- or 8-rayed. 
Three or four species from mountain-streams of North America, including one from 
Chihuahua. 
1. Rhinichthys simus. 
Rhinichthys simus, Garm. Science Observer, 1881, p. 61*; J ord. & Everm. Bull. U.S. Nat. Mus. 
xlvii. 1896, p. 3077; Meek, Publ. Columbian Mus., Zool. v. 1904, p. 79°. 
in the length, length of head about 4. Snout obtuse; mouth inferior; diameter of eye 
5 to 6 in the length of head. Dorsal 8-9, with 6 or 7 branched rays; origin above innermost ray of 
ventrals and nearly equidistant from tip of snout and base of caudal, Anal 8. 50 to 62 scales in a 
longitudinal series, 12 te 14 in a transverse series from origin of dorsal te lateral line, 8 to 10 between 
Depth ef body 4 to 43 
