DEC. 28, 1916. FISHES OF PANAMA MEEK AND HILDEBRAND. 335 



Color bluish black above; sides mostly silvery, the margin of scales 

 brown; pale below. Very young often with a dark lateral band, which 

 later becomes only faintly visible. A dark caudal spot present at all 

 ages, but most distinct in young. The spines of first dorsal black, the 

 membranes yellowish green; second dorsal and caudal yellowish green 

 at base; ventrals yellow; pectorals plain translucent. Very young some- 

 times with reddish fins. 



There are 118 specimens, ranging from 40 to 255 mm. in length, in 

 the present collection which we have identified as this species. These 

 were collected at various points on both slopes of Panama, mostly in the 

 lowland streams, some even were taken in brackish water, and a few 

 are from upland streams. On the Atlantic slope it was taken at several 

 points in the Chagres Basin and in small coastal streams at Porto Bello 

 and Toro Point. On the Pacific slope it was found everywhere, except 

 in the Rio Tuyra Basin. 



After careful study of our material, together with specimens from 

 Cuba and Guatemala, we find it impossible to retain the two nominal 

 species, A. monticola and A. nasutus. The only reason for keeping the 

 two separate heretofore apparently was the alleged difference in the 

 thickness of the upper lip. We, however, find that in our large series 

 this is a variable character upon which no reliance can be placed. We 

 have specimens with a thin upper lip, some with a thick lip, and nearly all 

 stages between. These occur indiscriminately on both slopes, and in 

 the same rivers and pools. However, the thick-lipped form occurs 

 more frequently among our Pacific slope specimens than among those 

 from the Atlantic. 



Habitat: Mexico; Central America; both slopes of Panama and the 

 West Indies. 



70. Agonostomus macracanthus Regan. 



Agonostomus macracanthus Regan, Ann. & Mag. Nat. Hist., Ser. 7, 



XIX, 1907, 65, and Biol. Cent. Amer., Pisces, 1907, 69, PI. XI, fig. i 



(Rio Guacalate, Guatemala). 



Head 3.4 to 3.55; depth 3.1 to 3.3; D. IV-I, 8; A. II, 12; scales 41 

 to 42. 



Body compressed, rather deep; head low; snout conical; 3.25 to 

 3.55 in head; eye 4.34 to 4.9; interorbital 3.05 to 3.25; mouth rather 

 large, slightly oblique; the upper jaw projecting; the upper lip quite 

 thick; maxillary reaching nearly to vertical from middle of eye, 2.44 to 

 2.6 in head; teeth as in preceding species; gill-rakers short, about 20 on 

 lower limb of first arch; scales large, ctenoid, extending forward to inter- 

 orbital region, about 12 rows between anterior rays of second dorsal and 



