164 
OSTARIOPHYSI, 
1. Couesius adustus. 
Couesius adustus, Woolman, Bull. U.S. Fish. Comm. xiv. 1894, p.57'; Jord. & Everm. Bull. 
U.S. Nat. Mus. xlvii. 1896, p. 83257; Meek, Publ. Columbian Mus., Zool. v. 1904, 
p- 82°. 
Hab. Mexico, Rio Conchos in Chihuahua ! 2, 
21. HYBOPSIS, Agass., 1854. 
Hybopsis (part.), Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 314. 
Differs from Yuriria in having the body less compressed, the snout obtuse, the mouth horizontal and sub- 
terminal or inferior, the isthmus wider, and the ventral fins 7- or 8-rayed. 
About fifteen species from the United States, from the Great Lakes to the Rio 
Grande and its southern tributaries. 
1. Hybopsis zstivalis. 
Gobio estivalis, Girard, Proc. Ac. Philad. 1856, p- 189°, and U.S. & Mex. Bound. Surv., Fish. p. 49, 
t. 57. figs. 17-29 (1859) *. 
Hybopsis estivalis, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 316°; Meek, Publ. 
Columbian Mus., Zool. v. 1904, p. 81°. 
Depth of body 4 to 5 in the length, length of head 4. Snout as long as postorbital part of head ; diameter of 
eye 4 in the length of head. Dorsal 9, with 7 branched rays; origin nearer to tip of snout than to base 
of caudal; longest ray shorter than the head; free edge concave. Anal 8-9. Pectorals sometimes 
nearly reaching the ventrals, which are inserted below the origin or anterior part of dorsal. 33 to 36 
scales in a longitudinal series, 5 or 6 in a transverse series from origin of dorsal to lateral line, 34 or 4 
between lateral line and base of ventral. Caudal peduncle twice as long as deep. Upper part of body 
with small dark spots ; a dusky stripe on each caudal lobe. 
Hab. Muxico, Rio San Juan in Nuevo Leon!24; Rio Conchos in Tamaulipas 4 (Meek). 
Here described from six specimens, measuring up to 65 mm. in total length. 
2. Hybopsis sterletus. 
Ceratichthys sterletus, Cope, in Wheeler’s Surv., Zool. v. p. 652, t. 27. fig. 8 (1876). 
Depth of body 53 in the length, length of head 4. Snout nearly as long as postorbital part of head; diameter 
of eye 43 in the length of head. Dorsal 9, with 7 branched rays ; origin nearer to tip of snout than to 
base of caudal; longest ray nearly as long as the head; free edge concave. Anal 9. Pectorals extending 
to the ventrals, which are inserted below the origin of dorsal and reach the anal. 38 scales in a longi- 
tudinal series, 53 in a transverse series from origin of dorsal to lateral line, 4 between lateral line and 
base of ventral. Caudal peduncle twice as long as deep. Coloration uniform ; fins pale. 
Hab. Rio Grande: 
San lidefonso!; Juarez ( Woolman). 
Here described from a single specimen of 40 mm. 
