ICTIOBUS.— MOXOSTOMA. 145 



4. Ictiobus labiosus. 



Carpiodes labiosus, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 29, fig. 6 \ 

 Ilah. Mexico, Valles in San Luis Potosi i. 



f). Ictiobus tumidus. 



Ictiobus tumidus, Girard, U.S. & Mcx. Bound. Surv., Fish. p. 34, t. 19. figs. 1-4 (1859) '. 

 Carpiudes vellfer (part.), Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 167'. 

 Carpiodes tumidus, Meek, Publ. Columbian Mus., Zool. v. 1904, p. 27 \ 



Ilah. Texas and North-eastern Mexico : 



Texas -, Rio Grande at Fort Brown i ; Rio Soto Marina and Rio Forlon in 

 Tamaulipas ^. 



Differs from /. meridionalis especially in having the body deeper, the pectoral 

 tin 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. 



Mo.rostoma, 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. 



Synoi^sis of the Mexican Species. 



I. Posterior edge o£ lower lip straight, transverse; dorsal fin o£ 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 j the width of head ; interorbital width 2;^ to 23 in the length 

 of head, which is 4^ to 4f m the length of the fish (in specimens of 130 to 

 150 mm.) ; pharyngeal teeth 10 — 10 2. austrinuni. 



Width of mouth | to ^ the width of head ; interorbital width 2^ to 2| in the 

 length of head, which is 4 to 43 in the length of the fish (in specimens of 

 105 to 150 mm.) ; pharyngeal teeth 6 — 6 3. mascotce. 



II. Posterior edge of lower lip notched; dorsal fin of 2 simple and 12 branched 



rays 4. parvideus. 



BIOL. CENTK.-AMEK., Pisces, Novcmler 1907. U 



