Family XIV. AtherinidjE. 177 



Basin of the Rio Lerma. 



Head3f; depth $%: D.-v-n ; A. 19; scales 14-62. Body elongate, 

 compressed; snout pointed, 3 in head; lower jaw slightly the longer; 

 mandible 2^ in head; mouth rather small, oblique; teeth in jaws in 

 narrow bands, none canine-like; no teeth on vomer or palatines; eye 

 3^ in head; origin of dorsal fin slightly nearer base of caudal than tip 

 of snout; pectoral \ l / 3 in head; ventral 2^ in head; base of anal i 1 /^ ; 

 scales small, edges slightly crenate, those in nape and before pectoral 

 fin much reduced; gill rakers slender, about 27 on first gill arch; verte- 

 brae 23 + 20 =43. 



Color light brownish, translucent; a dark silvery lateral band; 

 scales with few dark punctulations. Length about 5 inches. 



This is the most abundant member of the genus in Lago de Patz- 

 cuaro. It is probably quite widely distributed throughout the Lerma 

 basin. 



165. Chirostoma promelas Jordan & Snyder. 



Chirostoma promelas Jordan & Snyder, Bull. U. S. Fish Comm., 

 1900, 136, fig. 14; Lago de Chapala (market of Guadalajara): 

 Jordan & Evermann, Bull. 47, U. S. Nat. Mus., 1900, 3160: 

 Evermann & Goldsborough, Bull. U. S. Fish Comm., 1902, 182; 

 Lago de Chapala: Pellegrin, Bull. Mus. Hist. Nat. Paris, 1901, 

 205; Estado de Jalisco: Meek, Field Col. Mus. Pub. 65, 1902, 

 115; Ocotlan ; La Palma. 

 Basin of the Rio Lerma. 



Head 3-?-; depth 4f; D. iv-n; A. 19 or 20; scales 15-53 to 56. 

 Body elongate, compressed; head slender, triangular; mouth large, 

 very little oblique; snout pointed, 2%'va the head, upper jaw the longer; 

 maxillary reaching vertical from anterior margin of the orbit; teeth 

 large, not arranged in definite rows, none on vomer or palatines; diam- 

 eter of eye 5 2 /?, in head ; origin of spinous dorsal midway between base 

 of caudal and nostril; pectorals \ 2 /i in head; ventrals 2%; base of anal 

 1 Yi in head; scales with crenate edges, those on nape and in front of 

 pectorals much reduced in size; gill rakers slender, 24 on first gill arch. 

 Color silvery, translucent, a distinct dark lateral band; scales on 

 upper part of the body with dusky edges ; snout and jaws black. Length 

 about 7 inches. 



This is the only member of the group which has the upper jaw de- 

 cidedly longer than the lower. Only a few specimens known. 



Subgenus Lethostole Jordan & Evermann. 



166. Chirostoma sphyrasna Boulenger. 



Chirostoma sphyrcena Boulenger, Ann. & Mag. Nat. Hist., 1900, 55; 

 Lago de Chapala: Meek, Field Col. Mus. Pub. 65, 1902, 116. 



