Maryland Geological Survey 357 



Hollow appear to be Patapsco forms aud it is possible that Zamiopsis 

 insignis may have continued after the close of the Patuxent. 



One feature worthy of comment is the venation. The laterals are 

 not gathered together in systems with a main trunk to each segment of 

 the pinnule as previously described and figured, but they branch more 

 uniformly and fork less frequently and pursue approximately parallel 

 courses, suggesting greatly the venation of the modern cycad-genus 

 8tangeria. 



Occurrence. — Patuxent Formation. Fredericksburg, Chinkapin 

 Hollow ( ?), Virginia; New Reservoir ( ?), District of Columbia. 



Collection. — U. S. National Museum. 



Zamiopsis petiolata Fontaine 



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

 p. 166, pi. Ixvi, fig. 3. 



Description. — " Frond bipinnate or tripinnate, principal rachis \\'ith 

 a strong wing; primary pinna terminating abruptly in a large incised 

 pinnule similar to those lower down; pinnules petiolate, attached by the 

 midnerve, prolonged into a stout petiole, alternate, cut obliquely into 

 oblong or subelliptical obtuse pinnules, in the lower part of the ultimate 

 pinnae turned outwards. These graduate in the upper parts of the same 

 into lobes and teeth of the same general character. The summit of the 

 ultimate pinna is a broad oblong segment, ending in several shallow 

 subacute teeth formed by the union of the lobes at the summit ; the ulti- 

 mate pinnae in passing towards the summit of the penultimate ones 

 diminish much in size, the pinnules and lobes passing finally into teeth ; 

 lateral nerves in each pinnule and lobe consisting of a nerve-bundle 

 which goes off very obliquely from a point near the lower end of the pin- 

 nule or lobe, branching near the insertion, and curving out to enter the 

 pinnule or lobe, the branches forking again once or twice, with the ulti- 

 mate nerves very long and slender, owing to their deep forking." 

 —Fontaine, 1890. 



This rare plant represents a development of the Zamiopsis deniata 

 type in the direction of greater subdivision of the pinnas and the forma- 



