MAY. 1902. THE ICHTHYOLOGY OF MEXICO MEEK. in 



.C- Anal rays 17; gill-rakers 4+21 = 25; scales 48-12; body light, 

 translucent, slightly compressed; depth 5^. Origin of spinous dorsal 

 slightly nearer tip of snout than base of caudal. PATZCUARO. 



Anal rays 13 or 14; gill-rakers 44.17=21; scales 54-12. 

 Body dark, opaque, scarcely compressed; depth 6*; origin of spinous 

 dorsal nearer tip of snout than base of caudal by a distance greater 

 than diameter of eye. ZIRAHUEX. 



ff. Origin of spinous dorsal midway between base of caudal fin 

 and anterior margin of the orbit, or the nostril; anal rays 17 to 19; 

 scales 54-15; gill-rakers 4-1-15 = 19. Species of large size. 



HUMBOLDTIANUM. 



ee. Scales with crenate edges; origin of spinous dorsal nearer 

 base of caudal than tip of the snout; anal rays 18 to 24. (Let/iostole.) 



h. Snout short, 3^ in length of the head, being equal to or 

 shorter than the diameter of the eye. Species of small size. 



/. Scales in lateral series 49, transverse 13: anal base equals the 

 length of the head, its rays 21. CHAPAL^E. 



//". Scales in the lateral series 62, trans verse -14; base of anal fin 

 i^ in the length of the head, its rays 19. GRAXDOCULE. 



h.h. Snout long, 2| to 2 in the length of the head: diameter of eye 

 4^ to 5^ in head. Species of large size. 



k. Upper jaw decidedly longer than the lower, mandible 2j in 

 the head: tip of snout black: base of anal fin i| in the head, its rays 

 19 or 20; scales 53 to 56-15; teeth large, not in definite rows: snout 2^ 

 in head: diameter of eye 5^: gill-rakers 54-19. PROMELAS. 



kk. Lower jaw decidedly longer than the upper: mandible li to 

 2! in the head; tip of jaws not black (dusky in some specimens). 



/. Scales between dorsal fins very small, more than 20 in a 

 series between the fins; scales 60 to 70-22: gill-rakers ?-)-23: teeth 

 large anteriorly, canine-like, not arranged in definite rows: mandible 

 2 in head. SPHR.^XA. 



//. Scales in the region of dorsal fins larger, fewer than 15 in a 

 series between the two fins. 



///. Scales in the lateral series 54 to 60. 



n. Lower jaw projecting but little beyond the upper mandible, 

 about 2! in head. 



o. Teeth weak, in patches, not arranged in definite rows; gill- 

 rakers 4+23: scales 56 to 60-18; mandible 2^ in head. i.rcus. 



oo. Teeth large and strong, in two definite rows, the larger teeth 

 on inner row of upper jaw and outer row on lower: mandible 2j in 

 head; gill-rakers 5-(-2o; scales 58-20. LERM^E. 



nn. Lower jaw projecting much beyond the upper, mandible \\ 



