68 Proceedings of the Rojal Physical Socletif. 
behind the teeth of the lower jaw, five small warty-like papillae 
projecting behind it into the mouth. In front of the mouth 
you have the free transverse slightly-fringed margin of the un- 
divided nasal membrane, with its frenum in the mesian line, 
attaching it to the upper jaw ; it is also free at its outer margins 
(leaving an obliquely placed nasal opening on each side), and 
thus forms altogether a double flap, which covers the large trans- 
versely placed nasal organs. About 1^ inch behind the mouth, 
the double row of spiracles or gill openings, five in number 
on each side, run backwards in a curved direction; and about 
J an inch behind them, but in the mesial line, at the forepart 
of the abdomen, you find a small projecting body which mea- 
sures tV^s of an inch in length by |th of an inch in breadth ; 
it is 3y2_ths inches distant from the mouth, and from it to the 
anal opening measures 4 inches ; it appears to be the last re- 
mains of the now all but absorbed vitellus or yolk of the egg, 
the umbilical bag which nourished the fish in its younger 
stage of existence. The whole length of the fish along its 
under surface is, from the snout to the middle of the anal 
opening, 10 inches, and from the anal opening to the extre- 
mity of its slender and pointed tail 30 inches. 
The tail is rounded above ; it measures about an inch in 
breadth at its insertion to the body, and tapers to a minute 
point. Nearly opposite the insertion of the spine above, there 
begins on the under surface a narrow fin without rays, which 
projects about one-tenth of an inch, and runs with a low and 
free margin for about 3J inches down the grooved under-surface 
of the tail. 
As this fish advances in age, its body and tail are described 
as becoming very rough and spiny above, and, in some 
instances, the tail is said to become comparatively short, at 
least in the old male. The fish is described as using its tail 
as a weapon of defence, striking its enemies with this for- 
midable weapon, and inflicting severe and even dangerous 
wounds. It is stated to feed on small eels, which are abun- 
dant in the mud of the river's bed. 
It is with much diffidence I have ventured to lay before the 
Society a notice of this African fish. It belongs to the Sub- 
Family of the Trygonince ; and if the peculiarity of the 
spine or spur on the tail is a character of any importance, 
