370 POLYCENTRID.T. 



Fam. 34. POLYCENTRID^. 



Body compressed, elevated, covered -svith scales. Lateral line none. 

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

 portion being the more developed. Ventrals thoracic, composed of 

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

 branchite hidden ; no superbranchial organ. 



Cai'nivorous fishes from the fresh waters of Tropical America. 



Synojysis of the Genera. 



Mandible without barbel 1. Polycenteus. 



Mandible with a barbel 2. Monocirriius. 



1. POLYCENTRUS. 



Polycentrus, Miill. ^- Trosch. in Schomb. lieis. Brit. Guyana, iii. p. 622, 

 and Horce Ichthyul. iii. p. 25 ; Gill, Ann. Lye. New 3 'ork, 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. Prteorbital and prajoperculum serrated ; barbel none. 

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

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

 stcgals ; the gill-membranes not united ; gills four ; pseiidobranchiae 

 hidden. 



Fresh waters of Tropical America. 



In deference to the opinion of the authors of the Horce leJiiliyolo- 

 gica, we formerly placed this genus in our family of Prist tpomalklce 

 (vol. i. p. 396). Gill has indicated for it a sej)arate subfamily of 

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

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

 division, intermediate between the true Acanthopterygians and the 

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



1. Polycentrus schomburgkii. 



311111. c")- Trusch. I. c, and Hur. Ichthyol. iii. taf. 5. fig. 2. 



D. '-^. A. ^. L. lat. 29. L, transv. 14. 



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 maxillary extends beyond the vertical from 

 the middle of the eye. Pra3operculum with seven series of scales. 

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



