The ultrastuctures of cuticle and ocelli of 11 species of Isotomidae have been observed. They arequite different from each other

and it can be used as important characters in the taxonomy of Isotomi-dae. The ultrastructures of ocelli of 5 species which belong to the lower genera of Isotomidae are simi-lar to the normal cuticle of their boby surface; whereas in other higher genera

they are more smoothand obviously differ from the neighbouring body surface.