Macrostomorpha taxonomy and phylogeny

The small reniform eyes are not embedded in the tissues of the ganglia. The penis-stilette is a long, curved funnel which extends from a widened proximal base to end in a slightly bent obliquely truncated terminus. The stilette termination is distinctly provided with a thin lip which projects slightly beyond the opening proper. p. 195 The sperm cell in this form is a spindler-shaped structure which is much shorter than usual for Macrostomum. Chromatin granules are present in the anterior region of the cell, while posteriorly directed setae are absent. p. 196