the Elder Pliny, The Boys' and Girls' Pliny
“ It is impossible to cut them asunder with iron, and they are only to be broken with a strong blow, upon which they separate, just like foam of the sea when dried up. It has never yet been discovered of what material they are made; some persons think that they are formed of sharp fish-bones, as it is on fish that these birds live. They enter rivers also; their eggs are five in number.The sea-mew builds its nest in rocks, and the diver in trees as well. ”
