770 SYSTEMATIC PALEONTOLOGY 



siderably narrowed and somewhat thickened lower portion of the sporo- 

 phyll; its isolated occurrence without any evidence of its having been a 

 member of a disk; the functional pollen sacs in the proximal instead of 

 the distal part of the series. These features all suggest that the cyclic 

 arrangement, if present in the ancestors of Williamsonia marylandica, 

 had been succeeded by a spiral arrangement which approximated the 

 ordinary conifers or cycad strobilus rather than that organ as exemplified 

 in the familiar Cycadeoidea or Williamsonia types of the older Mesozoic. 

 There is the further possibility that Williamsonia was dioecious for if the 

 form be considered a fragment of a foreshortened disk, it is difficult to 

 explain the abortion of the distal pollen sacs and the development of the 

 basal ones. 



Williamsonia marylandica is relatively small, much smaller than the 

 majority of known forms, although Halle 1 has described a still smaller 

 form as Williamsonia pusilla from the Jurassic of Graham Land. It is 

 distinguished from Williamsonia delaivarensis Berry by its smaller size, 

 constricted basal portion, more acuminate tip and thinner texture. There 

 are a number of true Williamsonias that are deeply cleft as the present 

 form would have to be, as for examp]e, Williamsonia oregonensis Fontaine 

 from the Oregon Jurassic or Williamsonia virginiensis Fontaine from the 

 Lower Cretaceous of Virginia, and the same feature is noticeable in the 

 allied genus Cycadocephalus of the Ehsetic. 



The only other possible interpretation of the present fossil is that it 

 may represent some unknown coniferous type comparable with the fruit- 

 ing specimens of Palissya described by Nathorst 2 from the Ehsetic of 

 Sweden. In any event it emphasizes the fact that the Upper Cretaceous 

 contains many unknown gymnospermous types that await the lucky dis- 

 covery of the field paleobotanist. 



Occurrence. MAGOTHY FORMATION. Little Eound Bay, Anne 

 Arundel County. 



Collection. Johns Hopkins University. 



1 Halle, Wiss. Ergeb. Schwed. Sudpolar-Exped. 1901-03, Bd. iii, Lief, xiv, 

 1913, p. 70, pi. vi, fig. 12. 



* Nathorst, Kgl. Svenska Vetens.-Akad. Handl., Bd. xliii, No. 8, 1908. 



