for natural history.

The Psammead reached out a hairy arm from its basket and pointed
to a heap of mud at the edge of the water.

'What do you call that?' it said; and as it spoke the heap of mud
slid into the river just as a slab of damp mixed mortar will slip
from a bricklayer's trowel.

'Oh!' said everybody.

There was a crashing among the reeds on the other side of the
water.

'And there's a river-horse!' said the Psammead, as a great beast
like an enormous slaty-blue slug showed itself against the black
bank on the far side of the stream.

'It's a hippopotamus,' said Cyril; 'it seems much more real
somehow than the one at the Zoo, doesn't it?'

'I'm glad it's being real on the other side of the river,' said
Jane. And now there was a crackling of reeds and twigs behind
them. This was horrible. Of course it might be another
hippopotamus, or a crocodile, or a lion--or, in fact, almost
anything.

'Keep your hand on the charm, Jane,' said Robert hastily. 'We
ought to have a means of escape handy. I'm dead certain this is
the sort of place where simply anything might happen to us.'