170 OSTAEIOPHTST. 



Anal 20-27 (3-4/17-24<) ; maxillary extending to below anterior part or 

 middle of eye; diameter of eye 2^ to 3^ in the length of head (in specimens 

 of 60 to 120 mm.) 3. mexicanus. 



II. Interorbital width 3?r to Si in the length of head; 14-17 gill-rakers 



on the lower part of the anterior arch 4. a7igustifroiis. 



1. Tetragonopterus aeneus. 



Tetrayompierus cenexis, Giinth. Proc. Zool. See. 1860, p. 319 ', and Cat. Fish. v. p. 326 (1864) '; 



Jord. &Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 334'. 

 Tetragonopterus fasciatus (part.), Giinth. Cat. Fish. v. p. 322 (1864) \ 

 Tetragonopterus microphthalmus (part.), Giinth. t. c. p. 324". 

 Tetragonopterus panamensis, Giinth. 1. c." ; Steind. Denkschr. Ak. Wien, xli. 1879, p. 166, t. 1. 



figs. 1 & 2 '. 

 Tetragonopterus humilis, Giinth. t. c. p. 327 '. 

 Tetrago7wpterns finitimus, Boconrt, Ann. Sci. Nat. (.5) ix. 1868, p. 62'; Vaill. & Pellegr. Bull. 



Mus. Paris, 1903, p. 325 '". 

 Tetragonopterus belizianus, Bocourt, 1. c." ; Vaill. & Pellegr. 1. c.''. 

 Tetragonopterus (erstedii (Kriiyer, J\IS.), Liitken, Vid. Medd. 1874, p. 229". 

 Tetragonopterus rutilus (part.), Jord. & Everm. 1. c.'*. 



Tetragonopterus aneus (part.), Meek, Puhl. Columbian Mus., Zool. v. 1904, p. 86 ". 

 ? Astyanax nasutus, Meek, Publ. Columbian Mus., Zool. vii. 1907, p. 108 '°. 

 Astijanax rutilus mrstedii, Eigenmann & Ogle, Proc. U.S. Nat. Mus. xxxiii. 1907, p. 22''. 

 Astyanax rutilus nicarayuensis, Eigenmann & Ogle, t. c. p. 23 '". 

 Astyanax rutilus ceneus, Eigenmann & Ogle, t. c. p. 24 ". 

 Aslyanax fischeri, Eigenmann & Ogle, t. c. p. 26"'. 



Depth of body 2^ to 3^ in the length, length of head 3| to 4^. Snout obtuse, not longer than eye. the 

 diameter of which is 3 to 3.' in the lengtli of head; interorbital width 2| to 3 in the length of head. 

 Maxillary extending to the vertical from anterior edge of eye or sometimes a little beyond ; maxillary 

 teeth to G. 11 to 1-3 gill-rakers on tlie lower part of the anterior arch. 32 to 40 scales in a 

 longitudinal series, 6 to 8 in a transverse series from dorsal fin to lateral line, 5 to 7 between lateral line 

 and root of ventral fin. Dorsal 10-12 ; origin behind the vcntrals ; longest ray from | to as long as the 

 head ; free edge of the fin nearly straight. Anal 25-33, with 3 or 4 simple and 22 to 29 branched rays ; 

 free edge usually slightly emarginate. Pectoral from | to as long as the head, usually reaching the 

 ventrals, which often extend to the origin of anal. Caudal forlvcd. Caudal peduncle about as lonn- as 

 deep. Olivaceous above, silvery below ; a bluish-silvery lateral band ; often a dark humeral spot; usually 

 a blackish oblong spot on the caudal peduncle, produced on the middle caudal rays. 



Ilalj. Mexico i", Rio Papaloapam ^'^ {Bidler, Gadoio, Meek), Oaxaca i {Salle) ; Bkitish 

 Honduras ^^ ^- {Paris Mus., Itohertson) ; Guatemala ^'^, Eio Motagua -^ Lake 

 Yzabal '^, Huamuchal '\ llio Guacalate ^, and Lake Amatitlan ■' ^ {Godman & Salvm), 

 Chinautla '^ 10 ; Nicaeagua i". Lake jNicaragua i^\ Lake Managua ^'^ and Rio San 

 .Tuan 13 {Cojjenhagen Mus.) ; Costa Rica {Underwood); Panama "^ -o {Godman & 

 Salvin), Rio Mamoni^'', Rio Chagres. 



Here described from a large series of specimens, measuring up to 120 mm. in total 

 length, including the types of the species and of T. microphtlmhms, T. panamensis, 

 and T. humilis, and co-types of T. oerstedii and T. helisianus. 



