The paper is a study of horseshoe crab (limulid) behaviour, based on their ichnites from the Middle Jurassic rocks of the Cleveland Basin, Yorkshire, UK, from a succession spanning a period of c. 8 myr. Five named ichnospecies have been recognized from this sequence as having a limulid maker: Selenichnites hundalensis, S. rossendalensis, Kouphichnium aff. variabilis, K. cf. arizonae and Crescentichnus tesiltus, as well as unassigned ichnospecies (K. isp. indet., S. isp., S. isp. indet., and C. ispp. indet.). These traces have been interpreted as showing behavioural patterns during burial, feeding, locomotion and probing. The occurrence of these traces in both non-marine and marine strata together with their presumed lifestyle is compared to what is known of extant horseshoe crabs, and any difference in lifestyle is discussed.