The Night Shapes

de James Blish

The continent lay before them, vast areas of it unexplored, its forests, plains, jungles and mountains teeming with forms of life unknown to modern man. Here the witch doctors reigned supreme, using their inexplicable and remarkable powers on men and beasts. The purpose of the safari was mysterious, its members an oddly assorted group of people, unlikely to have any sane objective in common. And they soon discovered science was helpless in the face of prehistoric realities...