358 Systematic Paleontology 



tion of a petiole. It is very doubtfully distinct from that type, with 

 which it is also associated. It is not at all certain that the winged 

 rachis is not a feature due to compression during fossilization. 



Occurrence. — Patuxent Fokmation. Fredericksburg, Virginia. 



Collection. — U. S. National Museum. 



Zamiopsis laciniata Fontaine 



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

 p. 164, pi. Ixvl, figs. 1, 5-8. 



Description. — '' Frond very large and wide-spreading, probably arbores- 

 cent; ultimate pinnse alternate, the. lower ones very long, rapidly 

 diminishing in length and size in ascending towards the summit of the 

 principal pinnas, having a distinctly winged rachis, and terminating in 

 a variously shaped segment formed of united pinnules or lobes, usually 

 three in number; pinnules very variable in size and shape, mostly long, 

 ribbon-shaped, slightly narrowed to the base and attached by the entire 

 base, decurrent, and united to form a wing, cut very obliquely into a 

 few lobes of varying depth, which are elongate-oblong or narrowly 

 ovate in shape, and nearly always placed on the posterior margin of 

 the pinnule. The lobes toward the summit of the pinnules pass some- 

 times into acute ' triangular teeth, which are turned outwards. The 

 pinnules at the summit of the ultimate pinnae pass into more or less 

 united lobes, which vary a good deal in shape, being somewhat much 

 narrowed and even w^edge-shaped at base^ and incised into a varying 

 number of irregularly shaped teeth; nerves of the pinnules departing 

 from a short mother nerve at the base of the pinnules, forming three 

 branches, these diverging slightly in a fiabellate manner; branches 

 very long, slender, but distinct, outer branches simple or once or twice 

 forked, the inner one forking several times and approaching the character 

 of a midnerve; leaf-substance thick and leathery .'' — Fontaine, 1890. 



This plant is of rare occurrence and combines the features of the 

 genera Ctenopteris Saporta, Ctenidium Heer, and Scleropteris Saporta. 

 It also suggests the latter aiithor's genus 8tenopteris. It is confined 

 to the lowermost Potomac in the Virginia area and has not been dis- 

 covered in Maryland. 



