Ever since 1931, when we found remains of crocodiles and fish at several sites, we have known that a non-mammalian fauna was present in the Olduvai deposits, but it is only during the past three years that any considerable quantity of fossils of this natuie has been found in situ.

It has not been possible to obtain detailed reports upon any of the non-mammalian fossils in time for inclusion in this volume. The following summary, however, indicates the range of material. The following categories have been found:

1. Mollusca

2. Pisces

3. Amphibia

4. Reptilia

5. Aves

MOLLUSCA

Fossil mollusca occur in Beds I, II and IV. In Bed IV the commonest are those representing Unio sp. In Beds I and II there is a small bivalve akin to Corbicula, as well as specimens allied to Melanoides tuberculata.

PISCES

Fossil fish remains occur in Beds I, II and IV. Some are found in sands and silts, where they became imbedded in lake deposits at death. The majority of the specimens, however, come from the living-floors of early man and were clearly part of his diet.

The presence of such fish as Tilapia and Cichlidae in certain deposits suggests that at these periods the lake contained a considerable amount of water.

So far, only a brief preliminary report on the fish remains is available, based on itiaterial from two living-sites in Bed I, two in Bed II, and various sites in Bed IV.