Maryland Geological Survey 355 



the upper surface; penultimate pinnae very long, ultimate pinnae or pin- 

 nules usually closely placed, narrowed to the base, mostly linear-lanceo- 

 late or oblong-lanceolate, the lower ones generally cut obliquely into 

 pinnules which are denticulate, but pass above into denticulate or spinous 

 teeth and terminate in two or more spinous teeth ; nerves of the pinnules 

 and lobes mostly composed of a midnerve which goes off very obliquely 

 and curves strongly outwards, sending off obliquely and alternately 

 lateral branches, which are forked or simple and curve upwards towards 

 the summit of the segment; in the lobes and teeth the lateral nerves go 

 off very obliquely and fork once or twice, having very long ultimate 

 branches; nerves, although fine, very distinct/' 



These plants are closely related to the genus Ctenopteris and possibly 

 they should be included in that genus. They differ in having the 

 pinnse narrowed at the base, correlated with which the vascular strands 

 are usually gathered into a single vein. Although Professor Fontaine 

 compared these forms with the cycads he decided that the fern-like char- 

 acters predominated. In the present treatment they are referred to the 

 cycadophytes. The latter on a priori grounds would be expected to have 

 included forms with branched fronds and other fern-like characters 

 such as are possessed by Zamiopsis and Ctenopteris. It may be noted 

 also that this is the habit in the modem genus Bowenia: That the 

 toothed pinnules not only are present in a number of modern cycad 

 genera, but are especially well developed in EncepJialartos : And that the 

 venation characters are very like those of the recent cycad-genus 

 Stangeria. 



With a single doubtful exception the genus is confined to the 

 Patuxent formation, and with but a single doubtful occurrence it is 

 confined to the Virginia area. 



Zamiopsis dentata (Fontaine) 

 Plate LVI, Figs. 1, 2 



Scleropteris dentata Fontaine, 1890, Mon. U. S. G-eol. Surv., vol. xv, 1889, 



p. 153, pi. Ixili, figs. 3, 4. 

 Zamiopsis pinnatifida Fontaine, 1890, Mon. U. S. Geol. Surv., vol. xv, 1889, 



p. 161. pi. Ixi, fig. 7; pi. Ixii, fig. 5; pi. Ixiv, fig. 2; pi. Ixvii, fig. 2. 



