16. PIABUCINA. 311 



Fifth Group. TETRAGONOPTERINA. 



Characinida? with an adipose fin and with a short dorsal, with 

 the teeth in both jaws well developed, compressed, notched or 

 denticulated, with the gill-membranes free from the isthmus, and 

 with the nasal openings close together. 



South America and tropical Africa. 



16. PIABUCINA. 



Piabucina, Cuv. Sr Val. xxii. p. 161. 



Dorsal fin placed in, or somewhat behind, the middle of the length 

 of the body, immediately behind the ventrals ; anal rather short. 

 Body oblong, covered with scales of moderate size ; belly rounded. 

 Lateral line none. Cleft of the mouth of moderate width : teeth 

 rather small, tricuspid, those of the intermaxillary in a single, those 

 of the mandible in a double series ; maxillary with a very few small 

 teeth ; palate toothless. Nostrils close together. Gill-openinge wide, 

 the gill-membranes not being attached to the isthmus. 



Maracai'bo. 



1. Piabucina erythrinoides. 



Cuv. 8f Val. I, c. pi. 641. 



B. 4 D. 10. A. 12. V. 8. L. lat. 37. 



The origin of the dorsal fin is nearly in the middle between the 

 end of the snout and the root of the caudal. The height of the body 

 equals the length of the head, and is contained five times and a 

 half in the total (without caudal) ; the lower jaw is longer than the 

 upper ; the middle postorbital very narrow. A blackish spot on the 

 base of the anterior dorsal rays, another on the root of the caudal 

 fin. {Val.) 



Maracai'bo. 



2. Piabucina unitaeniata. 



D. 10. A. 11. V. 8. L. lat. 27. L. transv. 8. 



The height of the body equals the length of the head, and is one- 

 fourth of the total (without caudal). Lower jaw obtuse, projecting 

 beyond the upper ; the mnxillary extends beyond the anterior margin 

 of the orbit. The diameter of the eye is two-thirds of the width of 

 the interoi-bital space, somewhat less than the extent of the snout, 

 and one-fifth of thp length of the head. The middle postorbital is 

 as high as long. The origin of the dorsal fin is nearer to the root of 

 the caudal than to the end of the snout, and behind the vertical from 

 ' ie base of the ventral. Adipose fin very small ; caudal forked, with 

 its basal half scaly. The length of the pectoral is three-fifths of that 

 of the nead, and somewhat more than one-half of its distance from 

 the ventral. Ventral shorter than pectoral. Brownish ; an indistinct 



