1. The embryonic and the early post-embryonic development of Ummidis fragaria (Ctenizidae) was studied on preserved and living materials.
2. The embryonic development of Ummidia closely resembles that of other mygalomorphs.
3. In about three weeks the eggs hatch and the prelarvae emerge. About two days after hatching they take the first molt and become the larvae. The larval stage lasts about four weeks and the larvae transform into the protonymphs. The early postembryonic development of Ummidia is very similar to that of Ischnothele (Dipluridae).
4. In Ctenizidae, Dipluridae and Theraphosidae the larval stage consists of two phases: pL, L or L, pN, whereas in Atypidae only one phase, L. In the primitive spider, Heptathela also the larval stage is only one phase, L. From a point of view of comparative embryology, therefore, the Atypidae may be the most primitive among the mygalomorph spiders.