AGOSIA. — EHINICHTHTS. 165 



22. AGOSIA, Girard, 1856. 

 Agosia, Jord. & Evenn. Bull. U.S. Nat. Mus. xlvii. 1896, p. 308. 



Differs from Hylopsis 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 oscuhts, Girard, Proc. Ac. Philad. 1856, p. 186 \ and U.S. Mex. Bound. Surv., Fish. p. i7, 



t. 27. figs. 9-12 (1859) ^ 

 Argyreus notabilis, Girard, 1. 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 =. 



Hah. Gila River in Arizona : 



Recorded in Mexico from the Rio Santa Cruz ^ * in Northern Sonora, a tributary 

 of the Gila. 



2. Agosia chrysogaster. 



Agosia chrijsogaster, Girard, Proc. Ac. Pliilad. 1856, p. 187 ', and U.S. & Mex. Bound. Surv., Fisli. 

 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 *. 



Sab. Gila River in Arizona ; Sonora and Western Chihuahua : 



Rio Santa Cruz ^ -, Hermosillo ■^ and Rucker Caiion * in Sonora ; Sierra Madre 

 in Chihuahua ■*. 



23. RHINICHTHYS, Agass., 1850. 

 Rhiiiicfithijs, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 305. 



Body elongate, little compressed. Mouth non-protraetilo, suhterminal or inferior ; a small barbel at the end 

 of each maxillary. Pharyngeal teeth compressed, hooked, in two series, 2, 4 — 4, 2 or 1. Gill-openings 

 separated by a broad isthmus. Scales small. Dorsal and anal fijis 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. Rhiniclithys simus, 



Rhiaichthys simus, Garm. Science Observer, 1881, p. 61 ' ; Jord. Si Everm, Bull. U.S. Nat. Mus. 

 xlvii. 1896, p. 307' : Meek, Publ. Columbian Mus., Zool. v. 1904, p. 79'. 



Depth of body 4 to 4| 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 to 14 in a transverse series from origin of dorsal to lateral line, 8 to 10 between 



