240 A JOURNEY UP THE RIVER CONGO. 
Land crabs are numerous near the estuary of the Congo, 
especially inhabiting the mangrove swamps along the 
tidal river. They are amongst the weirdest things on a 
tropic shore, as they emerge from their holes in the black 
mud and march forth in armies after the retreating tide, 
rushing at the garbage strewn upon the ooze, and 
devouring everything devourable with unflagging appetite. 
Then, as the step of a human being approaches, they 
scuttle back to their many burrows of divers size and 
depth, and appear and disappear so rapidly that they seem 
like some formal illusion of the “ zoetrope.” It is great 
fun to intercept an unfortunate land-crab on the way back 
to his burrow. He knows perfectly well which is his, and 
would immediately make for it; but if you urge and 
exasperate him, and poke him up with your stick (not 
carrying your humour so far as to hurt the poor crusta- 
cean), he will in despair try to enter the retreat of one of 
his fellows, who will so smartly and spitefully repel him 
that you may out of pity stand aside, and let him race off 
to his own hole and pop down it in a trice. Sometimes a 
large crab pursued will make for too small a burrow, and 
get “stuck at the opening, in which case, brought to bay, 
he uses his unequal- sized claws like a boxer, shielding 
himself with one and nipping with the other. 
A river like the Congo naturally abounds in fish, but 
very little is as yet known about its ichthyology. It 
seems, however, from the data we possess, to resemble 
oreatly the Upper Nile, and to offer many identical species 
and genera. There are many clupeoid, cyprinoid, and 
percoid forms. The siluroid group is represented by 
several species, among them the huge “ bagré” * of the 
Portuguese, a fish with a smooth, shiny skin and a large 
flat head, in which the eyes, very small and colourless, are 
placed wide apart. At each corner of the mouth there is 
a long reversed tentacle. Also a ganoid, Polypterus, very 
common and very spiteful. I give an illustration here, 
engraved from my original study. This fish had the 
* Bagrus sp. 
