416 MESOZOIC FLORAS OF UNITED STATES. 



When it is remembered that the chances of preservation for siUfica- 

 tion of the less woody and more pulpy tissue of the cycads were probably 

 much less favorable than that of the conifers, one is permitted to suppose 

 that the preponderance of the latter, as suggested by the more common 

 occurrence of their remains, may not, after all, have been very considerable. 



DESCRIPTION OF THE SPECIES OF MARYLAND POTOMAC CYCADS. 



The whole number of specimens that have come into my hands for 

 description to the present date (September, 1902) is 105. A final study 

 of this material results in the separation of them into nine specific groups ; 

 in other words, nine distinct species. I refer them all to the genus 

 Cycadeoidea of Buckland, which has been fully described in earlier papers 

 audits systematic position discussed (seep. 216). It may be illustrated 

 by two groups representing the finest specimens of the Maryland cycads. 



Genus CYGADEOIDEA Buckland. 

 Cycadeoidea marylandica (Fontaine) Capellini & Solms-Laubach. 



PL LXXXI; PI. LXXXII; PL LXXXIII, Figs. 1, 2, 4; PL LXXXIV, Figs. 1, 2 

 PL LXXXVII, Figs. II, 3, 5, 6, 7; in, 1, 4; iv, 4, 5, 12, 1.3, 14; v, 2, 3, 5, 6, 7, 17 

 PL LXXXVIII; PL LXXXIX, Figs, ii, 3, 4, 7; in, 2, 5, 8; PL XC; PL XCI 

 PL XCII. 

 1860. Cycas sp. Tyson: First Report State Agric. Chem. Maryland, p. 42. 

 1870. Bennettites sp. Carr.: Trans. Linn. Soc. London, VoL XXVI, p. 708. 

 1879. Cycadoidea sp. Font. : Am. Journ. Sci., 3d Ser., VoL XVII, p. 157. 

 1889. Tysonia Marylandica Font.: Potomac Flora (Monogr. U. S. Geol. Surr., 



VoL XV), p. 193, pi. clxxiv-clxxx. 

 1892. Cycadeoidea Marylandica (Font.) Cap. and Solms. : Mem. ReaL Accad. Sci. 



1st. Bologna, Ser. V, VoL II, pp. 179, ISO, 186. 

 1897. Cycadeoidea Marylandica (Font.) Cap. & Solms. Ward: Proc. Biol. Soc. 

 Washington, Vol. XI, p. 9. 

 Trunks of medium or rather large size, almost always more or less 

 laterally compressed so as to be elliptical in cross section, conical in shape 

 or shghtly narrowed near the base with a terminal bud set in a slight 

 depression at the summit, simple, or in one specimen, apparently having 

 one branch; mineral constitution very variable according to mode of 

 preservation, but usually not hard, flinty, nor heavy and compact ; reddish, 

 pinkish, drab, or ash colored; 25 to 45 cm. high, 24 to 40 cm. in longer 

 and 12 to 26 cm. in shorter diameter, with a girth of from 70 cm. to one 



