370 POLYCENTRID.fi. 



Fam. 34. POLYCENTRID^. 



Body compressed, elevated, covered with scales. Lateral line none. 

 Dorsal and anal ftns long, both with numerous spines, the spinous 

 portion being the more developed. Ventrals thoracic, composed of 

 one spine and five rays. Teeth feeble. Gills thre^ or four ; pseudo- 

 branchiae hidden ; no superbranchial organ. 



Carnivorous fishes from the fresh waters of Tropical America. 



Synopsis of the Genera. 



Mandible without barbel 1. Polycentrus. 



Mandible with a barbel , 2. Monocirrhus. 



1. POLYCENTRUS. 



Polycentrus, MilU. ^" Trosch. in Schomb. Reis. Brit. Guyana, iii. p. 622, 

 and Horce Ichthyol. iii. p. 25 ; Gill, Atin. Lye. New York, 1 858, p. 371. 



Body compressed, elevated, covered with ciliated scales of mode- 

 rate size. Mouth very protractile. Small teeth in the jaws and on 

 the palate. Prseorbital and praeoperculum serrated; barbel none. 

 Dorsal and anal fins with numerous spines ; ventrals thoracic, com- 

 posed of one spine and five rays. Lateral line none. Six branchio- 

 stegals ; the gill-membranes not united ; gills four ; pseudobranchioc 

 hidden. 



Fresh waters of Tropical America. 



In deference to the opinion of the authors of the Hcrm IchtJiyolo- 

 gicce, we formerly placed this genus in our family of Pristipomatklce 

 (vol, i. p. 396). Gil] has indicated for it a separate subfamily of 

 Scicenidce, which he calls Polycentrince. It is evident, however, that 

 this genus, together with other American fishes, forms a separate 

 division, intermediate between the true Acanthopterjgians and the 

 Pharyngognaths, and allied to the Nandidce and Lahi/rinthici. 



1. Polycentrus schomburgkii. 



3fiHl. ^ Trosch. I. c, and Ilor. Icldhyol. iii. taf. 5. (ig. 2. 

 D. ±^. A. i^. L. lat. 29. L. transv. 14. 



8-7 7 



The height of the body is two-fifths of the total length, the length 

 of the head one-third ; the diameter of the eye equals the width of 

 the interorbital space, and is one-fourth of the length of the head (in 

 adult specimens) ; the raaxillaiy extends beyond the vertical from 

 the middle of the eye. Prtcoperculum with seven series of scales. 

 The first ventral ray produced. Brownish-olive, irregularly spotted 



