There can be little doubt that some of the Mesozoic and Tertiary species included under _Lycopodites_ agree more closely with the recent genus _Selaginella_ than with _Lycopodium_, but this does not constitute an argument of any importance against the restricted use of the designation _Selaginellites_ which we have adopted. From a botanical point of view the various records of _Lycopodites_ and _Selaginellites_ have but a minor importance; they are not sufficiently numerous to throw any light on questions of distribution in former periods, nor is the preservation of the material such as to enable us to compare the fossil with recent types either as regards their anatomy or, except in a few cases, their sporangia and spores. The Palaeozoic species are interesting as revealing less reduction in the number of spores produced in the megasporangia. Among existing Pteridophytes the genus _Isoetes_ agrees more closely than _Selaginella_, as regards the number of megaspores in each sporangium, with such fossils as _Selaginellites Suissei_ and _S. elongatus_. It would seem that in most Palaeozoic species heterospory had not reached the same stage of development as in the recent genus _Selaginella_ in which the megaspores do not exceed four in each sporangium. In _Selaginellites primaevus_, however, the heterospory appears to be precisely of the same type as in existing species. Lycostrobus. The generic name _Lycostrobus_ has recently been instituted by Nathorst[232] for certain specimens of a lycopodiaceous strobilus, from the Rhaetic strata of Scania, which he formerly referred to the genus _Androstrobus_[233]. _Lycostrobus Scotti_ Nathorst. Fig. 139.