FAMILY SILURID.E — PIMELODUS. 181 



tubular margin, and equidistant between the posterior nostrils and the margin of the upper jaw. 

 Sides of the upper jaw terminate in a movable accessory bone an inch long, to which is at- 

 tached a long flattened filament tapering to a fine point, and six inches long ; beneath this, at 

 the angle of the jaw, is a deep cavity. On the under side of the lower jaw, at a distance of 

 half an inch from the margin, are four cirri or barbels placed transversely : two on each side 

 of the jaw ; the two composing the middle pair rather more distant from each other, than from 

 the adjacent cirrus on each side. All these are somewhat compressed, but less so than those 

 at the angle of the jaw. Exterior to the outer barbels, on each side, are two or three fora- 

 mina in a regular series ; the two external communicating with the inside of the mouth, the 

 others merely blind cavities. These are not always present on both sides, and sometimes 

 they are ahnost obsolete. Mouth very capacious, with broad bands of small recurved equal 

 teeth in both jaws, and in the throat. Palate smooth. Tongue large and rounded, not free. 



The first dorsal fin obtusely pointed, higher than wide, and composed of one bony and six 

 branched rays. It commences eight and a half inches from the end of the snout, or a little 

 forward of a point reached by the tips of the pectorals. The bony ray is serrated, and ter- 

 minates in a soft flexible tip ; the third ray slightly longest. The adipose dorsal elongate, 

 rounded ; its tip reaching a point above the termination of the anal. Pectorals placed low 

 down, consisting of one stout articulated and serrated spine, and of nine branched rays ; the 

 lowermost small and indistinct ; the length of its base to its height as three to one. Ventrals 

 broad and rounded, consisting of one spinous and eight broad flat many-branched rays ; these 

 fins arise nearly beneath a point reached by the tips of the prostrate dorsal. The extremities 

 of the ventrals cover the vent and the posterior urinary meatus, which latter terminates in a 

 fleshy tubercle. Anal fin long and subequal, composed of twenty-six rays : the first ray short ; 

 the second and third successively longer ; the rest subequal as far as the twenty-second, when 

 they again become shorter, making the posterior termination of this fin regularly rounded : 

 its base to its height as three to one nearly. Caudal forked, with seventeen complete rays. 

 The rays of all the fins are so much enveloped in the common thick teguments, as to be 

 counted with difiiculty. The spleen is dark red, flat and rounded, with a flat accessory lobe 

 above. The liver large, transverse, with two lobes on the left, and a smaller one on the right ; 

 the gall-bladder is long and large, and attached closely to the substance of the liver. Stomach 

 exceedingly thick and muscular. Kidneys large, bifurcating backwards under the air blad- 

 der, and terminating in a large urinary bladder. Air-bladder large, long, with remarkably 

 thick coats ; anteriorly it ends in two pointed processes, with a laciniated border between 

 them ; a longitudinal wall or septum, as stout as the external coat, divides it into two equal 

 parts ; the anterior part is covered by a broad thin glandular substance, the uses of which 

 are unknown. The most curious fact in relation to the air-bladder, is that it communicates 

 with the alimentary canal, just under the diaphragm, by a duct two inches long, and sufli- 

 ciently large to admit a crow quill. 



Color. General hue olive-brown ; the upper part of the head and cheeks bluish ; the sides 

 of the body towards the tail, ash white, with occasionally large confluent black spots ; a few 

 irregular distant round black spots on the upper part of the body. Upper lip maculated with 



