MARYLAND GEOLOGICAL SURVEY 797 



Protophyllocladus subintegrifolius Hollick, 1907, Mon. U. S. Geol. Survey, 



vol. 1, p. 36, pi. v, figs. 1-6. 

 Protophyllocladus subintegrifolius Berry, 1911, Bull. 3, Geol. Survey of 



New Jersey, p. 98, pi. ix. 



Description. Leaves oblong to linear in outline and coriaceous in 

 texture, from 3 cm. to 17 cm. in length by 0.6 cm. to 3 cm. in 

 width. Apex usually obtuse, rarely pointed. Base decidedly and narrowly 

 cuneate to the short petiole. Margins entire below, above obtusely dentate 

 or undulate, with occasionally teeth which are acute. Midrib stout below 

 becoming attenuated above and frequently disappearing some distance 

 below the apex. Laterals numerous, close, immersed ; they branch at an 

 angle of about 20, running nearly straight and approximately parallel 

 to the margin, sometimes forking. Stomata scattered on both surfaces, 

 with typical guard cells. 



This is a widespread species ranging in considerable abundance from 

 Greenland (Atanebeds) to Alabama (Tuscaloosa formation), and west to 

 Kansas and Xebraska (Dakota sandstone). Originally referred to Phyt- 

 locladus by Lesquereux, his type is almost identical with certain phyllo- 

 clads of modern members of this genus. Subsequently discovered remains 

 from Kansas are considerably larger than the type, as are also a number 

 of the Greenland specimens. Some of the Earitan forms have a somewhat 

 different aspect, being long and narrow; sometimes the margins are 

 entire, often they are more or less sharply toothed. 



Much controversy has centered around these forms and especially 

 around the older Mesozoic forms referred to the genus Thinnfeldia 

 Ettingshausen, to which these later forms were once referred. The latter 

 genus has been referred successively to the conifers, ferns and cycads. 

 There has never been much doubt that the later forms were gymno- 

 spermous. The writer can positively affirm this conclusion, and also that 

 they are true phylloclads and not leaves in the strict morphological sense. 



Whether or not they are closely related to the modern genus Phyllocladus 

 is still in doubt, although there are some excellent arguments for such a 

 relationship. While fossil remains of undoubted relationship to Phyllo- 

 cladus are extremely rare, Gothan has described 1 wood of a similar type 



1 Gothan, Kgl. Svenska Vetens. Akad. Handl., Bd. xlii, No. 10, 1907. 



