238 
PIMELODUS ELON@ATUS, n. sp. (Pl. X. fig. B-) 
B.6. D.1/6. A.1l. V. 1/5. P.1/9. 
The body is elongated, compressed posteriorly ; head moderately 
broad and long, depressed, truncated anteriorly ; its length is con- 
tained six times and two-thirds in the total length of the fish. The 
snout is rather produced, nearly one-half the length of the head, 
truncated, with the upper jaw longest. The distance between the 
angles of the mouth is nearly equal to the length of the snout. Six 
barbels: that of the maxillary reaches nearly to the extremity of the 
pectoral fin ; the exterior pair of the mandibulary barbels are two- 
thirds the length of the interior, and extend to the base of the pec- 
toral; the interior pair are inserted somewhat before the outer ones, 
and rather more remote from each other than from the outer ones. 
The diameter of the eye is one-fourth of the length of the head, 
and nearer to the extremity of the operculum than to that of the 
snout. The width of the interorbital space is to the length of the 
head as 2:7. The head is covered superiorly with a very thin and 
smooth membrane ; the occipital process is long, and extends on toa 
small bony plate in front of the dorsal; this plate is also covered 
with skin, like the head. The lower edge of the operculum is straight ; 
the spine of the humeral bone is very indistinctly striated. The 
depth of the body, taken below the origin of the dorsal, is one-eighth 
of the total length; that of the tail, before the caudal, one-sixteenth. 
The pectoral extends to below the middle of the dorsal fin; its spine 
is shorter than the first rays, stout, compressed, with the interior 
edge spiny. The ventral has the first ray undivided, flexible ; it is 
inserted immediately behind the vertical from the dorsal, and does not 
extend on to the anal. The dorsal is higher than long ; the length 
of its base equals its distance from the head; the spine is slender, 
stiff, pungent, provided superiorly with a ray-like filament. The adi- 
pose fin is very long, its distance from the dorsal and caudal fins 
being nearly equal. Caudal deeply notched, with the lobes pointed ; 
the upper lobe is longer than the inferior, and its length is one- 
fifth of the total. The length of the base of the anal is 12 in its 
distance from the caudal; its margin is convex. Above uniform 
greyish, heneath whitish ; lateral line blackish ; dorsal and caudal 
minutely dotted with black. 
Hab. Fresh waters of Esmeraldas. 
inches. lines. 
EE peptic 7 sides preeene sn ney 8 
Benpthvol thethesd Fi 656 9So on ve cna wa 9 1.0 
= OLENETSNOULUS Wa, site 56.6 s. wiacais.c's, eis, 5 0 52 
Distance between the eyes............-.---- 33 
between the angles of the mouth .... 0 54 
DimMeteriGh Ebel MYON... oso ces Mise cares ae 
Pidight Gn teeiey ie Spo. Secas i ste asneaee, DERE 
et A ee Se! fotuisistid 20 0 5 
— of the first dorsal ray ............ aa yeroud 
Length of the upper caudal lobe ............ 1 4 
