MARYLAND GEOLOGICAL SURVEY 769 



Occurrence. KARITAN FORMATION. Shannon Hill, Cecil County, 

 Maryland; East Washington Heights, District of Columbia. 

 Collection. Maryland Geological Survey. 



CYCADOPHYTA 



CLASS CYCADOPHYTAE 

 order WILLI AMSONIALES 



Family WILLIAMSONIACEAE 



Genus W1LL1AMSONIA Carruthers 

 [Trans. Linn. Soc. Lond., vol. xxvi, 1868, p. 680] 



WILLIAMSONIA MARYLANDICA n. Sp. 



Plate LI, Figs. 5, 6 



Description. Staminate bract or sporophyll of a Williamsonia-like 

 form of small size. Sporophyll flat and relatively thin, smooth, about 

 14 mm. in length and 4 mm. in maximum width, spatulate-lanceolate in 

 outline, i. e., lanceolate-acuminate, widest distad and constricted and 

 somewhat thickened proximad. It bears on its upper (adaxial) surface 

 a double row of papillose markings which become fainter and fainter 

 distad until they are finally entirely obsolete toward the tip of the 

 sporophyll. These are interpreted as the cicatrices of synangia or pollen 

 sacs of which the basal four to eight pairs appear to have been functional. 



This form is of very great interest since the bulk of the described 

 Williamsonice and all those showing any details of their organization are 

 from very much older horizons. The present form is capable of interpre- 

 tation in terms of the ordinary Williamsonia morphology as a single seg- 

 ment of the staminate disk, which may be directly compared with such 

 well-known forms as Williamsonia whitbiensis so admirably restored by 

 Nathorst. 1 A well-marked form of this type, named Williamsonia dela- 

 warensis by the writer, is present in the Magothy formation of Maryland 

 and Delaware. Certain facts suggest an alternative hypothesis of the 

 organization of this Upper Cretaceous sporophyll. These are the con- 



1 Nathorst, Kgl. Svenska Vetens.-Akad. Handl., Bd. xlvi, No. 4, 1911, pp. 9-14 

 (see text fig. 3). 



