344 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. X. 



band at base of dorsal. A large black blotch present at base of caudal, 

 and most specimens with a black blotch on middle of side under tip of 

 pectoral. An occasional specimen also has many small dark spots on 

 sides. Fins plain translucent, or dusky; the vertical fins often with 

 small dark spots. 



There are 237 specimens, ranging from 20 to 250 mm. in length, in 

 the present collection. All are from the lower Chagres and its tribu- 

 taries. It was frequently found abundant in very brackish water, and 

 in Panama its range seems to be limited to the brackish and sluggish 

 streams of the Atlantic slope. 



The parents appear to guard their young for quite some time after 

 hatching. On one occasion it was noticed that two large fishes, evidently 

 of this species, were hovering very closely to numerous small ones, at 

 a place where the water was quite shallow. An attempt was made to 

 surround them with a seine. However, the adults by their very quick 

 movement made their escape. A large number of young was taken. 

 Only a few minutes after the seine was hauled the two large fishes reap- 

 peared and a second attempt at capturing them failed. The young 

 were all of about equal size, ranging from 20 to 24 mm. in length. 



Habitat: Lake Yzabal, Guatemala, south to Rio Chagres, Panama. 



75. Cichlasoma tuyrense Meek & Hildebrand. 



Heros margaritifer var. Steindachner, Denksch. K. Ak. Wiss. Wien, 



XLI, 1879, 161 (Rio Mamoni, Chepo). 

 Cichlasoma tuyrense Meek & Hildebrand, Field Mus. Nat. Hist. Pub., 



Zool. Ser., X, 1913, 89 (Rio Tuyra, Boca de Cupe, Panama). 



Head 2.75 to 3.45; depth 1.77 to 2.1; D. XVI to XVIII, usually 

 XVII, ii or 12; A. VI or rarely VII, 8 or 9; scales 34 to 41. 



Body deep, compressed; anterior profile nearly straight in young, 

 strongly convex in adult; no nuchal hump; head deep; snout moderately 

 pointed, 2.2 to 3.4 in head; eye 3.33 to 4.3; mouth rather small, terminal, 

 slightly oblique; maxillary failing to reach anterior margin of eye, 2.8 

 to 3.7 in head; the lips not thickened, the lower one not free at middle; 

 teeth in the jaws pointed, in bands, the outer one somewhat enlarged; 

 gill-membranes broadly connected across isthmus; gill-rakers short, 

 about 8 on lower limb of first arch; scales rather small, weakly ctenoid, 

 6 or 7 rows between lateral line and middle of base of dorsal; lateral line 

 interrupted under soft portion of dorsal, reappearing on the fifth row of 

 scales below its original course; origin of dorsal over posterior margin 

 of opercle, the spines strong, the last one 1.86 to 2.33 in head; the soft 

 portion with small scales at base, pointed and reaching well past base of 

 caudal in adult; caudal fin scaly at base, its posterior margin strongly 



