Polycistina or polycystines are a group of radiolarians, unicellular eukaryotes that produce intricate mineral skeletons.

These are presumably from Jeremie, Haiti, based on the text annotation and also how polycystines from Jeremie in Haiti were a subject of a book by Alfredo Truan Y Luard and Otto N. Witt. I suspect that neither Alfredo Truan Y Luard nor Otto N. Witt prepared this slide since the text is in English while Luard and Witt wrote in German. So the preparer is unclear.