The Dileptus belongs to the Phyllum Ciliophora. They are from 250-500 um long.

The Dileptus is an interesting ciliate with a long body that is pointed at the rear and, on the other end, a long flailing "neck". It is easy to identify a Dileptus when it is moving in the sample as you will see the "neck" beating back and forth.

The Dileptus is a unicellular ciliate that can be found in fresh and salt water, moss and soil. They are available from some science supply companies.