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XIV. — Description of a Siliirus^ known in De- 
merara by the name of Gilbacke, more pro- 
perly Geelbuik. 
By Dr T. S. Traill of Liverpool. 
(Read IQth December 1824.; 
A SPECIMEN of this silurus was lately examined, and its 
figure, while recent, drawn by my friend Charles S. Parker, 
Esq. who has since favoured me with the drawing, and the 
skin of the fish. 
It would appear to be a common species in the muddy 
waters of the rivers of Guyana, where they mingle with the 
sea ; and it is found at a considerable distance from the 
coast. When taken, it is used as an article of food. 
Feet. In. 
This specimen, when recent, measured - 3 4 
Its circumference at the first dorsal fin, - 1 11 
at the ventral fin, - - 0 lOg 
And it weighed S7 pounds. 
The true Dutch name is undoubtedly Geelbii'ik, or Yel- 
low belly. The upper parts are of a fine olivaceous green ; 
the sides and belly of a rich yellow. The body is thickest 
at the first dorsal fin ; and its section there would be nearly 
circular. It tapers quickly, yet equally, towards the tail, 
where it is slender. The head is broad, flat, and com- 
pressed. The vertex is defended by a rough bony plate of 
