64 AN INTRODUCTION TO THE STUDY OF FOSSILS 



This order formed the dominant vegetation of the Mesozoic 

 ranging from the Triassic into the Potomac (Comanchean). 

 It was exceedingly abundant during the Jurassic in North 



Fig. 21 b. — Restoration of flower bud of Fig. 21a, based upon many other 

 examples besides this figure. Nine of the eighteen staminate fronds (Jr.) are 

 shown folded with reduced pinnules (p.) bearing densely packed oval synangia, — 

 pollen sacs (in white). At the center is the pistillate portion of the flower, the 

 elongate conical receptacle (r.) covered externally with short stalked ovules (ov.) 

 separated by scales, br., bracts; ped., pedicle, or stalk, attaching the flower to 

 the stalk. (Both figures from Wieland.) 



