178 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. V. 



Chirostoma diazi Jordan & Snyder, Bull. U. S. Fish Comm., 1900, 

 137, fig. 15; Lago de Chapala (Guadalajara market): Jordan & 

 Evermann, Bull. 47, U. S. Nat. Mus., 1900, 3161. 



Basin of the Rio Lerma. 



FIG. 59. CHIROSTOMA SPHYR/ENA Boulenger. 



No. 6157 (Chirostoma diazi J. & S.). Leland Stanford Jr. University. 



Head 3^; depth 5; D. v-n; A. 20; scales 20-63 to 70. Body 

 elongate, moderately compressed; head large; upper jaw the longer; 

 snout 2^ in head; mouth large; teeth large anteriorly, growing grad- 

 ually smaller posteriorly, some canine-like, not arranged in definite 

 rows, no teeth on vomer or palatines; origin of spinous dorsal midway 

 between base of Caudal and eye; scales crenate, those on the dorsal 

 region very small, about 20 in a series between the dorsal fins; base of 

 anal if in head. 



Color light silvery, translucent; a narrow dark silvery lateral band. 

 Length about 8 inches. 



The small scales between the dorsal fins easily distinguishes this 

 species from those most nearly related to it. 



167. Chirostoma lucius Boulenger. 



Chirostoma lucius Boulenger, Ann. & Mag. Nat. Hist., 1900, 54; 

 Lago de Chapala: Meek, Field Col. Mus. Pub. 65, 1902, 15; La 

 Barca; Ocotlan; La Palma: Evermann & Goldsborough, Bull. 

 U. S. Fish Comm., 1902, 152; Lago de Chapala, Guadalajara 

 market. 



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

 1900, 139, figs. 16 and 17; Lago de Chapala, and Guadala- 

 jara: Jordan & Evermann, Bull. 47, U.S.Nat. Mus., 1900, 3162. 

 Basin of the Rio Lerma. 



Head 3^"; depth 4$; D. -13; A. 23 or 24; scales 17-56. Body 

 elongate, compressed; head pointed; snout 2f ; mouth large, the lower 

 jaw projecting; mandible 2% in head; teeth in bands in each jaw, all 

 small, none canine-like; no teeth on vomer or palatines; eye 5^ in 

 head; origin of spinous dorsal midway between base of caudal and 



