JURASSIC CYCADS FROM WYOMING. 185 



the small fragment No. 500.521, weighing 0.14 kg., which fits one of the 

 fractured surfaces of A^o. 500.7. In one other unimportant case two of 

 the later-acquired fragments proved to be the complements of each other, 

 viz, Nos. 500.176 and 500.229. 



Cycadella Knowltoniana Ward. 



PL XLVII, Figs. 1, 2. 



1900. Cycadella Knowltoniana Ward: Proc. Wash. Acad. Sci., Vol. I, p. 267, pi. xiv, 

 figs. 1-3; pi. xviii-xx; Twentieth Ann. Rep. U. S. Geol. Surv., 1898-99, 

 Pt. II, p. .396, pi. Ixx, figs. 1-3; pi. xci-xcv. 



This species, which, although represented by only two specimens in 

 the original collection, furnished the best illustrations of the generic 

 characters, is not absent from the material since received. The two 

 specimens, Nos. 500.94 and 500.498, resemble the type No. 500.76 

 sufficiently closel}^ to have formed parts of the same trunk, but this is 

 not proved by the discovery of any contiguous surfaces. Like that 

 specimen, the,y are both somewhat triangular sections bounded by radial 

 fractures, but showing considerable of the outer surface. In both, too, 

 as in the type, it is the transverse fracture that best reveals the structure. 

 If polished in the same way they would both doubtless show all the 

 characters of the genus. 



No. 500.94 is 8 cm. high and 13 cm. in diameter, which represents 

 a chord of the circumference, of which the arc is 19 cm., but the surface 

 is very irregular. The trunk was probably 15 cm. in diameter in this 

 direction. The radial thickness is 10 cm., which seems to include more 

 than half of the medulla, but this indicates a diameter in this direction 

 of about 18 cm. The trunk was therefore elliptical. The fragment 

 weighs 1.22 kg. 



No. 500.498 is a similar section, but the fractures are all oblique to 

 the axis. It is about 8 cm. high, 12 cm. in tangential direction, and 

 the same in radial direction. It weighs 1.41 kg. The outer coating of 

 ramentum is nearly 2 cm. thick in places, and the armor 3 cm., the petioles 

 and walls contrasting strongly in color, so as to show the structure to 

 good advantage even on the unpolished surface of the fractures. 



Two other specimens, Nos. 500.102 and 500.285, are referred to this 

 species, but these are one, since they perfectly fit each other, the latter 

 being only a thin plate lying on one of the fractured planes of the former. 



