THE UPPER CAMBRIAN BRADORIID OSTRACOD CYCLOTRON-LAPWORTHI IS A HESSLANDONID

Cyclotron lapworthi (Groom, 1902), one of the few British Cambrian bra doriid ostracod species known from alage number of specimens, is redes cribed. It has an interdorsum, thus indicating a hesslandonid affinity . The ontogeny of C. lapworthi does not demonstrate a clear distinctio n of its individual moult stages but does show marked changes in the d evelopment of nodes and lobes. C. lapworthi shows wide variation in ca rapace shape possibly indicating that its valves were thin and relativ ely flexible. In England and Canada C. lapworthi is restricted to the Upper Cambrian Olenus Zone. C. lapworthi may also occur coevally in th e Upper Cambrian of Sweden.