The present day classification of animal life falls into two great
divisions: (1) _Protozoa_, representing those composed of a single cell;
and (2) _Metazoa_, those whose bodies are composed of many cells. The
Protozoa, so far as known, form a single division or branch of the
animal kingdom, and the Metazoa comprise various higher branches. In the
following table the divisions are given from the highest forms to the
lowest, rather than in the reverse order frequently given, and sets out
the chief characteristic and animal examples of each division.