The few spelaeogriphacean taxa now known provide some interesting information as to some possible paleoenvironmental trends. Both of the Recent forms, P. brasiliensis and S. lepidops, are found in cavernicolous freshwater systems in the southern hemisphere. A. novascotica, on the other hand, is interpreted as having lived in a near shore marine habitat on the east coast of what is now North America (Schram 1974). Whether this is exactly true or not is not clear. Certainly the Carboniferous deposits containing Acadiocaris are marine. However, these deposits are black shales, and this has been suggested by others to reflect relatively deep-water habitats (e.g., see Heckel & Batemann 1975, O‘Neil & Schram 1975). Nevertheless, a distinct transition in environmental preferences has taken place at some point during the history of this group. Sometime between the Carboniferous and the Late Jurassic, certainly by the time of L. quadripartitus, a shift from marine to freshwater lacustrine habitats appears to have occurred. This shift might have been concurrent with invasion of cavernicolouos and/or ground water habitats.