42 2 Memoir Sears Foundation for Marine Research 



Anal fin: length of base 42. Scales: ca. 60, mostly missing.^i 



Pelvic fin: length 10.5. Fin rays: dorsal 15; anal 47;^^ pectoral 



Pectoral fin: length 23. 14. 



Distance from snout to origin of: dorsal 44. Ventral scutes: 26.'^ 



Body strongly compressed, its greatest thickness scarcely a third of its depth, its 

 greatest depth 3.25 in SL; the dorsal outline anterior to dorsal nearly straight, the 

 ventral outline strongly convex. Caudal peduncle 2.85 in head. 



Scales mostly lost; the scales on middle of side below base of dorsal scarcely 

 deeper than long, with 4 or 5 vertical striae, only the posterior one complete ; not very 

 closely imbricated ; the exposed part of scale notably greater than half of its depth, the 

 margin nearly smooth. Ventral scutes well developed, 20 in advance of pelvic fins 

 and 6 behind them. 



Head 4.0 in SL, its depth at vertical from slight crossgroove at occiput 4.2. 

 Snout definitely shorter than eye, without a definite median notch, 4.45 in head. 

 Eye 2.9. Interorbital 10 in head. Cheek fully as deep as long. Maxillary narrowly 

 rounded posteriorly, reaching below anterior margin of pupil, 1.85 in head. A soft 

 ligament between premaxillary and maxillary. Mandible projecting strongly, its tip 

 scarcely below dorsal outline of head, its margin within mouth rising rather strongly, 

 forming an obtuse angle, 1.75 in head. Gill rakers at angle of first arch scarcely half 

 of length of eye, 19 on lower limb of first arch. Teeth small; a few in a single row 

 on anterior part of mandible, a series on premaxillary and on margin of maxillary, 

 and bands of granular teeth on palatines, pterygoids, and tongue. 



Dorsal fin high anteriorly, its longest rays reaching far beyond tip of last ray if 

 deflexed, only a little shorter than the head, its origin nearer to margin of snout than to 

 base of caudal by a distance equal to length of snout and eye, its distance from margin 

 of snout 2.3 in SL. Caudal forked (damaged), the lower lobe evidently the larger; small 

 scales covering most of fin. Anal fin long, scarcely elevated anteriorly, its anterior rays 

 not forming a definite lobe, its origin under last ray of dorsal and equidistant between 

 posterior margin of eye and base of caudal, its base 2.4 in SL; a scaly sheath present. 

 Pelvic fin long (for an Ilisha'), inserted rather less than an eye's diameter in advance of 

 vertical from origin of dorsal and nearer to origin of anal than to base of pectoral, 2.3 

 in head; a short broad axillary process present. Pectoral fin reaching beyond base of 

 pelvic by a distance fully equal to diameter of pupil, 4.3 in SL, 1.05 in head; the 

 short free axillary process only a little more than a third of the length of fin. 



Color. Old preserved specimen grayish above, yellowish to silvery below. Upper 

 surface of snout and tip of mandible dark brown ; a brownish area behind eye. All fins 

 with dusky punctulations, these few and scattered on pelvic, most numerous on dorsal, 

 caudal, and upper half of pectoral. 



Range. Known only from the Amazon. 



51. If Myers [gy: 63-64) is correct in referring /. apapae and /. iquitensis to the synonymy of this species, then the anal 

 rays vary from 47 (types of amazonica) to 52 (type of iquitensis), the scales from 57 to about 60, and the total number 

 of ventral scutes 25 or 26. — G. S. M. 



