io8 Field Columbian Museum — Zoology, Vol. VII. 



Astyanax nasutus sp. nov. 



Type, No. 5909, F. M. N. H.; length, 125 mm.; Lake Managua, 

 Managua, Nicaragua. 



Head 3.9 to 4.3; depth 2.7 to 2.9; D. 1.9; A. 25 or 26; scales 

 8-36-7. Body elongate, compressed ; profile between nape and end of 

 snout slightly concave; top of head quite flat; dorsal and ventral 

 outlines about equally convex ; snout long, its length ;^.;^ to 3.5 in head ; 

 maxillarv slender, its tip reaching past vertical from front of orbit, 

 its length 2 to 2.2 in head; chin very prominent; eye 2.9 to 3.1 in 

 head ; gill rakers slender, 8 + 11 ; origin of dorsal fin slightly behind 

 that of ventrals, its distance from tip of snout 1.9 in length of body; 

 base of dorsal 1.8 in its height, its height i.i in head; origin of anal fin 

 slightly behind base of last dorsal ray, its distance from snout 1.5 to 

 1.6 in length of body; base of anal 3.6 in length of body; pectoral 

 fins not reaching ventrals, length 1.2 to 1.3 in head; ventrals reach- 

 ing to or slightly past vent, length 1.6 to 1.7 in head; lateral line 

 complete, decurved. 



Color light olivaceous, a broad plumbeous band from upper edge of 

 opercle to base of caudal, broadening into a caudal blotch; humeral 

 spot present. 



Managua (12), 85 to 125 mm.; Cisplaya (i), 95 mm. 



Astyanax aeneus (Giinther). 



Head 3.9 to 4.4; depth 2.4 to 3.2; D. 1.9; A. 26 to 28; scales 

 8-38-6. Body compressed, more or less elongate; ventral outlines 

 usually more curved than the dorsal; profile from nape to end of 

 snout straight or concave; snout short, 3.7 to 4.2 in head; maxillary 

 slender, its tip reaching vertical from orbit, length 2.3 to 2.6; jaws 

 subequal ; mandible 2 to 2.4 in head ; eye 2.8 to 3.8 ; gill rakers slender, 

 7 to 9+10 or II ; origin of dorsal to tip of snout 1.9 to 2.1 in length 

 of body; base of dorsal ^ height of fin, its longest ray i.o to 1.3 

 in head; base of anal fin 3.1 to 3.5 in body, equalling or slightly 

 longer than head ; origin of anal fin behind vertical from base to last 

 ray of dorsal, its distance from tip of snout 1.5 to 1.6 in body; pectoral 

 fin in the deeper individuals reaching base of ventrals, in larger or 

 slender individuals falling short at this point by one or two scale 

 lengths; length of pectorals i.i to 1.3 in head; ventrals reaching 

 to or slightly past vent; length of ventral 1.5 to 1.7 in head; lateral 

 line decurved, complete. 



Color light olive, silvery, a dark lateral band from upper edge of 

 opercle to base of caudal ; one or two dark humeral spots ; an elongate 

 caudal blotch. There is a considerable amount of variation in this 



