OLDER POTOMAC^ OV VIlUilMA AND MARYLAND. 535 



shaft l)einji thou filled with water. This collection was made by Lester 

 V. Ward, David White, and Kol)ert T. Hill. They obtained 42 of the 

 cones, but these are less })erfect than the others. 



In 1S93 Mr. Arthui- Ribbitis collected 1 specimen. Xo. (V.WI of the 

 Woman's College of Baltimore, and in June, 1895, he ol)tained for the 

 State (Jeological Survey of Maryland 5 more of these same cones. These 

 bear the nuinl)ei- 570!) of that survey. On still another occasion he 

 "oUected wliat seems to l)e a cycadaceous fruit. 



The cones all seem to belong; to Athwtaxopsift cvpaiisa. and the 

 cycadaceous fruit is })iT)babl\- Ciicadcospcnmwi ocutuni. 



Athuotaxopsis expansa Fontaine. 



Pi. CIX, Figs. 12, i:^>. 



1889. Athroiaxopsi.9 expansa Font.: Potomac Flora (Monogr. U. S. Clcol. Survey, 

 Vol. XV), p. 241, pi. cxiii, figs. .5, .5a, 5b, 6; pi. cxv, fig. 2; pi. exvi, fig. 5; 

 pi. cxvii, fig. 6, pi. cxxxv, figs. 15, 15a. 15b, IS, 22 (cones). 



As already remarked, the cones collected l.)y Mr. J. B. Hatcher 

 came from the clay which yielded the dinosaurian remains described 

 by Professor Marsh from the Potomac strata of Maryland. These 

 dinosaurian fossils led Professor Marsh to maintain that the Potomac 

 formation of Maryland is of Jurassic age. The cones now in question 

 are of additional interest on account of their unusual mode of fossili- 

 zation. They are mud casts, and in most cases retain no trace of the 

 original vegetal)le matter. They vary a good deal in size, l)ut all seem 

 to belong to the one species, Athrotazopsis expansa. The largest are 

 18 mm. by 15 mm., and the smallest are not more than half as large. 

 The difference in size is probably due to a difference in their develop- 

 ment. They are often somewhat distorted from pressure. The normal 

 .shape seems to have been l^roadly oblong, but some are nearly spher- 

 ical. The fossil is composed of indurated mud deeply pitted with 

 depressions that sometimes take the exact form of the cone scales, 

 and the whole object retains pretty accurately the shape and size of 

 the original cone. Sometimes the pits retain a trace of carbonaceous 

 matter, from the vanished scale, lining the pit. The pits were evidently 

 caused by the decay of scales which persisted until the cone had been 

 outlined in mud. These cones are exactly like those of Athrotaxopsis 



