Lower Cretaceous diatoms from ODP Leg 113 site 693 (Weddell Sea). Part 2: Resting spores, chrysophycean cysts, an endoskeletal dinoflagellate, and notes on the origin of diatoms. Proceedings of the Ocean Drilling Program Scientific Results, 113 1990: 403-425. 411 [Zoological Record Volume 127]