146 OSTARIOPHYSI. 
1. Moxostoma congestum. 
Ptychostomus congestus, Girard, Rep. U.S. & Mex. Bound. Surv., Fish. p. 36, t. 21. figs. 5-8 (1859) °. 
Pitychostomus albidus, Girard, t. c. p. 86, t. 19. figs. 5-8 *. 
Moxostoma congestum, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 192, and 1900, 
fig. 91°. 
Myzostoma congestum, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 34°. 
Depth of body 4 in the length, length of head 4 to 4}. Diameter of eye 4 to 43 in the length of head, length 
of snout 23, interorbital width 2 to 21. Snout truncated anteriorly. Lips plicated; lower lip with a 
straight transverse posterior edge; width of mouth } to 2 the width of head. 44 to 46 scales in a 
longitudinal series, 6 or 7 in a transverse series from origin of dorsal fin to lateral line, 5 or 6 from 
lateral line to base of ventral fin. Dorsal 12, the 2 anterior rays simple; origin nearer to tip of snout 
than to base of caudal; free edge straight or slightly concave ; longest ray longer than the base of the 
fin. Anal 8, the 2 anterior rays simple, the fin, when laid back, extending to the basal part of the 
caudal, Pectoral as long as the head, nearly or quite reaching the ventral, which is inserted below 
the anterior part of the dorsal. Caudal emarginate. Caudal peduncle 13 as long as deep. Brownish 
above, yellowish below; dorsal dusky, other fins pale. 
flab. Rio Grande System; Rivers of Texas and Tamaulipas: 
R. Lampasas? and R. Salado! in Texas; R. Conchos in Chihuahua‘; 
R. San Juan in Nuevo Leon?4; R. Conchos and R. Soto Marina in Tamau- 
lipas 4, 
Here described from two specimens, 120 and 160 mm. in total length, from the 
Rio Soto Marina (Meek). The species attains a length of 350 mm. 
2. Moxostoma austrinum., 
Myxostoma austrina, Bean, Proc. U.S. Nat. Mus. 1879, p. 302’. 
Mowxostoma austrinum, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 192°. 
Myzostoma austrinum, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 35°. 
About 10 pharyngeal teeth on each side. Depth of body 44 in the length, length of head 43 to 43. 
Diameter of eye 52 to 54 in the length of head, length of snout 24, interorbital width 27 to 23. Snout 
truncated anteriorly. Lips plicated; lower lip with a straight transverse posterior edge; width of 
mouth 4 the width of head. 47 to 50 scales in a longitudinal series, 7 in a transverse series from origin 
of dorsal fin to lateral line, 6 from lateral line to base of ventral fin. Dorsal 12, the 2 anterior rays 
simple; origin nearer to tip of snout than to base of caudal; free edge straight or slightly concave ; 
longest ray a little longer than the base of the fin. Anal 8, with the 2 anterior rays simple, the fin, 
when laid back, extending nearly to the base of caudal. Pectoral a little shorter than the head, 
extending rather more than 2 of the distance from its base to the origin of the ventral, which is below 
the middle of the dorsal. Caudal emarginate. Caudal peduncle 1? as long as deep. Brownish above, 
yellowish below; dorsal dusky, lower fins pale yellowish. 
Hab. Mexico, Rio Mezquital and Rio Lerma Systems: 
Durango; Aguas Calientes and Ataquiza in Jalisco? ; Salamanca in Guana- 
juato?; Lake Chapala’; Morelia in Michoacan’. 
Here described from two specimens from Aguas Calientes (Jordan), 180 and 150 mm. 
in total length. The species grows to the same size as the preceding one. 
