Maryland Geological Survey 323 



Occurrence. — Patuxent Formation. Link Gulch, near Arbutus, 

 Baltimore County.' 



Collections. — Johns Hopkins University, Yale University, U. S. Na- 

 tional Museum, Maryland Academy of Sciences, Goucher College of 

 Baltimore, McGill Universit}'-, and South Carolina College. 



Cycadeoidea Tysoniana Ward 

 Plate XLIII 



Cycadeoidea Tysoniana Ward, 1897, Proc. Biol. Soc, Washington, vol. xi, 



p. 11. 

 Cycadeoidea Tysoniana Ward, 1906, Men. U. S. Geol. Surv., vol. xlviii, 1905, 



p. 432, pi. Ixxxvii, figs. 1, 5; v, 4; pi. xciii. 



Description. — Trunk medium sized or large, more or less compressed 

 laterally; leaves slightly ascending; leaf scars arranged in spiral rows, 

 9 mm. high, 22 mm. wide, subrhombic, empty to some depth, petioles 

 persistent at base, the vascular bundles arranged in one row near the 

 exterior and a group near the centre, often persisting after the decay 

 of the remaining substance; ramentuin walls thin, often with a layer 

 of spongy substance in the middle, wrinkled on the edges; reproductive 

 organs few and small ; armor 5 cm. thick ; libro-cambium zone sometimes 

 distinct, 3 mm. thick ; woody zone 6 cm, to 8 cm. thick ; consisting of a 

 broad, parenchymatous layer 4 to 6 cm. thick, and a narrow inner vas- 

 cular zone 1 cm. thick, the latter usually between open tissue without 

 and within, its inner wall strongly marked with longitudinal grooves; 

 medulla distinct and homogeneous, light and porous. 



This species differs from Cycadeoidea marylandica in the larger leaf 

 scars, thinner walls, thicker armor, and the great paucity of reproduc- 

 tive organs, and from Cycadeoidea McGeeana in the normal shape of the 

 trunk and its greater size. 



Cycadeoidea McGeeana Ward 

 Plate XLIV 



Cycadeoidea McGeeana Ward, 1897, Proc. Biol. Soc, Washington, vol. xi, 



p. 12. 

 Cycadeoidea McGeeana Ward, 1906, Mon. U. S. Geol. Surv., xlviii, 1905, p. 



434, pi. Ixxxvii, figs, iii, 3, 10; iv, 15; v, 8, 9, 19, 20; pi. Ixxxix, figs, ii, 



1, 8; iii, 4, 9, 10; pi. xciv. 



