Maryland Geological Survey 333 



Zamites BucManus Seward, 1895, Wealden Flora, pt. ii, p. 79, pi. iii, figs. 



1-5; pi. iv; pi. viii, fig. 1. 

 Dioonites BucManus Fontaine, 1906, in Ward, Mon. U. S. Geol. Surv., vol. 



xlviii, 1905, pp. 244, 479, 483, 486, 517, 534, 538, pi. Ixvi, figs. 16, 17; pi. 



cvii, fig. 2; pi. cviii, fig. 1. 

 Dioonites BucManus ? Knowlton, in Diller, Bull. Geol. Soc. Am., vol. xix, 



1908, p. 386. 



Description. — '' P. fronde piniiata, pinnis circa 1-2 dm. longis, 4-7 mm. 

 latis, altemis, linearibus, subremotis, subangulo acute adnatis, nervis 

 creberrimus, tenuissimis instructis; rliachide crassiuscula." — Ettings- 

 hausen, 1852. 



Fronds very large, attaining probably the length of a metre or more; 

 maximnm width 25 cm. to 30 cm. ; rachis stout, epidermis of the rachis 

 and. pimiffi thick and durable; leaves thick and leathery; pinna; varying 

 much in dimensions, distance, shape, and termination; linear-acute, 

 sometimes closely placed, sometimes remote, those in the middle part 

 of the frond the most commonly found, these diverge at an angle of 45'', 

 those of the upper part become more and. more oblique, until at the sum- 

 mit they occur in the prolongation of the rachis; the terminal pinnse 

 much shorter and. narrower than those lower down; length varying, 

 attaining in some cases 25 cm. ; slightly narrowed to the base and at- 

 tached by the whole width of the base, obliquely placed and decurrent; 

 veins fine, not prominent, very closely packed, forking at the base, paral- 

 lel, and terminating without convergence in the summits of the leaflets; 

 some of the outer ones ending in the margins a little below the summit. 



In the material collected in the vicinity of Dutch Gap Canal on the 

 James Eiver, Virginia, the leaf substance is often preserved on the im- 

 pressions as a thick lignitic sheet. From such a specimen collected 

 over 20 years ago by Prof. Fontaine, at the locality kno^^^l as the Fishing- 

 Hut, above Dutch Gap Canal (U. S. F. M., No. 3773), pieces of the 

 epidermis were suitably prepared for microscopic examination, and a 

 number of interesting features were made out. Below a magnification 

 of 100 diameters the outlines of the epidermal cells appear as rows of 

 small, narrow-walled, almost square rectangles, the irregularly scattered 

 stomata showing as cells of darker color. With a higher power (385 



