ICTIOBUS.—MOXOSTOMA. 145 
4. Ictiobus labiosus. 
Carpiodes labiosus, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 29, fig. 6°. 
Hab. Mexico, Valles in San Luis Potosi |. 
5. Ictiobus tumidus. 
Ictiobus tumidus, Girard, U.S. & Mex. Bound. Surv., Fish. p. 34, t. 19. figs. 1-4 (1859) *. 
Carpiodes velifer (part.), Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 167 ?. 
Carpiodes tumidus, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 27°. 
Hab. Texas and North-eastern Mexico : 
Texas *, Rio Grande at Fort Brown!; Ric Soto Marina and Rio Forlon in 
Tamaulipas °, 
Differs from J. meridionalis especially in having the body deeper, the pectoral 
fin longer, and the dorsal rather more elevated anteriorly and perhaps with 
fewer rays. 
Girard described and figured his fish as having 29 rays, and Meek gives the number 
as 24, The former seems often to have given 1 or 2 in excess of the actual number, 
whilst the latter would sometimes count the 3 anterior simple rays as one. 
2. MOXOSTOMA, Rafin., 1820. 
Mowostoma, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 187. 
The distinctive characters of this genus are the short dorsal fin, large scales, complete lateral line, small 
inferior protractile mouth, jaws without cartilaginous sheaths and compressed pharyngeal teeth. 
There are about 24 species from the United States east of the Rocky Mountains and 
from Mexico. 
Synopsis of the Mexican Species. 
I. Posterior edge of lower lip straight, transverse; dorsal fin of 2 simple and 10 or 11 
branched rays. 
A. Pectoral as long as the head, nearly or quite reaching the ventral . . . 1. congestum. 
B. Pectoral shorter than the head, not reaching the ventral. 
Width of mouth 3 the width of head; interorbital width 2} to 23 in the length 
of head, which is 44 to 43 in the length of the fish (in specimens of 130 to 
150 mm.); pharyngeal teeth 10—10. . . . 2... ee ee ee  Q. ustrinum. 
Width of mouth 2 to 4 the width of head; interorbital width 25 to 2? in the 
length of head, which is 4 to 44 in the length of the fish (in specimens of 
105 to 150 mm.) ; pharyngeal teetth6—6 . . «© . «© - «© + © we + + 8. mascote. 
II. Posterior edge of lower lip notched ; dorsal fin of 2 simple and 12 branched 
rays... . 4. parvidens. 
BIOL. CENTR.-AMER., Pisces, November 1907. U 
