Maryland Geological Survey 307 



flora with a large number of species and individuals. They were in gen- 

 eral of a lofty arborescent habit, with a high structural organization. 

 Mesozoic remains are extremely rare and ill defined, although several 

 Cretaceous species have been described under the generic name 8elag- 

 mella. ISTone, however, come from as low a horizon as does the Mary- 

 land specimen.^ The modern species are small in size and of wide geo- 

 graphical distribution, especially within the tropics, where they are larger 

 and show greater specific differentiation than elsewhere. About five hun- 

 dred existing species have been described. They are heterosporous and 

 possess a ligule, as do their Paleozoic allies, and like Lepidocarpon ^ and 

 Miadesmia^ among the latter, they are sometimes quasi-seedbearing.'' 

 The modern forms have doubtless been derived from Paleozoic forms 

 which have always been herbaceous rather than from the complex arbo- 

 recent types by reduction, one of the few herbaceous Paleozoic plants 

 known, Miadesmia membranacea^ suggesting what such an ancestral type 

 may have been like. 



Selaginella marylandica Fontaine 

 Plate XLI, Figs. 1, 2 



Selaginella marylandica Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., 

 vol. xlviii, 1905, p. 553, pL cxv, figs. 9, 10. 



Description. — Fragmentary remains of dichotomously branching stems 

 of sympodial habit with two laterally attached rows of minute leaves 

 1 and 1.5 mm. in length. Leaf substance firm, with a thick midrib. 

 Leaves somewhat falcate, widest near the base, which is slightly cordate. 

 Possibly the leaves were four-ranked, the other rows being obscured or 

 present on the counterpart of the impression which was not collected. 



'■ See Halle, Einige krautartige Lycopodiaceen Palaozoischen und Meso- 

 zoischen Alters, Arkv. fiir Botanik, Stockholm, 1907, Band vii. No. 5. 



- Scott, Ann. of Botany, vol. xiv, 1900, pp. 713-717. 



* Benson, Rept. Brit. Assn. Adv. Sci., Belfast, 1902, p. 808. 



*Lfyon, Bot. Gaz., vol. xxxii, 1901, p. 170. 



= Bertrand, Ass. fr. Ad. Sc, 23e sess,, Caen, 1895, ii, p. 588. 

 Benson, Phil. Trans. Roy. Soc. Lond., vol. 199B, 1908, pp. 409-425, pis. xxxiii- 

 xxxvii. 



