Viable cysts collected from natural sediments were induced to excyst. Ten cyst-theca relationships, first established elsewhere, were confirmed for British Columbia (B.C.). These were: Gonyaulax tamarensis, Protoperidinium aspidotum, P. claudicans, P. conicoides, P. conicum, P. cf. denticulatum, P. leonis, P. oblongum, and P. punctulatum. Five cyst-theca relationships were established for the first time: Peridiniopsis cf. hainanensis, Protoperidinium sp. nov., P. thorianum, and two apparently new species of Gonyaulax. P. pentagonum was found to have a cyst different from the cyst of this species in the Atlantic. Forty-five samples from Recent sediments were collected along the coast of B.C. Twenty-three of the samples had very few cysts. Hidden Basin was the chief source of viable cysts for the excystment experiments. Ten cyst-based taxa were described from the sediment samples. These were: Operculodinium centrocarpum, the cyst of Scrippsiella faeroense (= Micrhystridium bifurcatum), Spiniferites belerius, S. bentori, S. bulloideus, S. elongatus, S. membranaceus, S. nodosum, and S. ramosus. Tanyosphaeridium sp. has been recorded previously as the cyst of Polykrikos schwarzi. Two new cyst-based taxa are described for the first time. These are a cyst of Protoperidinium sp., and Spiniferites "sp. A". Cyst assemblages in the Recent sediments of B.C. were similar to many temperate estuarine and neritic areas. Some cysts which are characteristic of these areas in other regions, have not yet been found in B.C. The relative importance of some cysts also varies from that found in similar sediments elsewhere. The dominance of Operculodinium centrocarpum in many of the cyst assemblages, including B.C., is a pattern typical of temperate estuarine conditions. Some cysts appear to be characteristically associated with fjord environments. Scrippsiella faeroense, for example, has been found in Norwegian fjords and Scottish sea lochs as well as some B.C. fjords and inlets. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate