eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 477 



Compressed and elongate ; dorsal profile lower than in P. furcrceus; interorbital 

 flattish, equal to or a little broader than the length of the eye. Suborbitals, pre- 

 orbitals, and preopercle cavernous and translucent; preorbitals turgid, overhanging 

 the very small, inferior mouth; maxillary concealed when the mouth is closed, 

 barely reaching the anterior margin of the eye. Posterior border of the preopercle 

 finely serrate; snout rather pointed, distinctly longer than the eye. Teeth all 

 minute and villiform. Gill-rakers 21 + 8 or 9, short, slender, and simple. 



Scales ctenoid, except on the suborbitals, snout, and mental region, where 

 they are cycloid; middorsal series of the head complete, the scales somewhat 

 enlarged. Caudal almost completely covered with scales in adult, thinly scaled 

 over the basal half in young specimens. Soft dorsal with scales on the basal one- 

 fourth to two-thirds. Anterior third of the anal with scales on the basal portion. 

 Lateral line little arched, becoming straight half-way between the last dorsal and 

 last anal rays. 



Highest dorsal spine 1.5-2 in the head; soft dorsal high, 2.5-3 in the head. 

 Caudal rhombic, 1.3 in the head in adults, more pointed in small specimens. Anal 

 with but one spine, which is scarcely heavier than the dorsal spines, 3.1 in the head. 

 Pectorals slightly longer than the ventrals, 1.5 in the head. Ventrals without 

 filaments. 



Ground-color greenish yellow, only a little darker above. Small specimens 

 with five to eight large, diffuse, dusky spots along the back and sides, the first 

 just in front of the spinous dorsal, a similar second series of five or six spots along 

 the lateral line, and a single spot on the opercle. Traces of the uppermost 

 series of these spots are retained in the adult. A number of small, flake-like, 

 dark brown spots in the region just below the spinous dorsal are present only in 

 the large specimen; while only the smaller specimens have the numerous large chro- 

 matophores on the snout and lower two-fifths of the sides. Distal half of the 

 spinous dorsal and the tips of all of the soft dorsal and caudal rays black; a very 

 small black bar on the base of each dorsal spine and a similar bar just above the 

 base on each ray of the soft dorsal; in addition to these fin-markings the large 

 specimen has a narrow black stripe, broken by the colorless rays through the middle 

 of the anterior two-thirds of the soft dorsal, and a series of black spots just in front 

 of the third, fourth, and fifth dorsal spines at one-fourth of the distance from their 

 bases. All scales with a pale silvery iridescence. 



This species resembles P. adspersus in its fin-rays and the spotted condition of 

 the dorsal, but differs from it especially in the size of the anal spine and arrange- 

 ment of the spots on the sides. 



