Hiatella – a Jurassic bivalve squatter

English late Jurassic (Middle Volgian) Hiatella occur in two habitats; firstly, as simple byssal nestlers on local hard substrates and, secondly, within Gastrochaenolites-type borings penetrating hard substrates. Most Hiatella occupy borings that they did not originally construct themselves, although ancestors as well as other bivalve genera could have been responsible. The morphology of the Mesozoic Hiatella is compared briefly with modern species which occur around the British Isles and which include both boring and nestling forms. A sequence of events is postulated for the formation of the Basal phosphatized Nodule Bed of the Spilsby Sandstone in Lincolnshire, and a palaeoenvironmental model is suggested for the East Midlands Shelf in Middle Volgian times.