424 



G. R. Wieland — American Fossil Cycads. 



The above interpretation and conception of the male cycad 

 inflorescences of the type then considered, I have now, from 

 extended study of much additional material in a far superior 

 state of preservation, confirmed as wholly correct and express- 

 ing their nature with precision. Defined in more detail, 

 this unexpanded fructification or strobilus is a series of from 

 twelve to twenty closely appressed fertile, morphologically 

 Marattiacean fronds, of semicircinnate prefoliation (or better, 

 inflexed prefloration), with twenty or more pairs each of simple 

 and reduced synangia-bearing pinnules, — these fronds being 

 inserted so closely as to appear on the same level, and fusing 

 basally so as to form an hypogynous staminate disk enclosing 



Figure 1. — Cycadeoidea. Diagrammatic sketch of longitudinal section through 

 the bisporangiate strobilus. At the center is the apical cone closely invested by 

 a zone of short-stalked abortive (?) ovules and in terseminal scales. On the left 

 is a single frond of the hypogynous staminate disk, with much reduced pinnules 

 bearing densely crowded synangia. On the right a similar fertile frond is arbi- 

 trarily shown in an expanded position. Exterior to the fronds are the hairy 

 bracts. About f natural size. 



a receptacle ending as a conical-shaped abortive (?) ovulate 

 strobilus. The essential organs are surrounded and in the 

 earlier stages enclosed by a series of acuminate and regularly 

 imbricating hairy bracts, the entire inflorescence developing 

 between the leaf bases, and later emerging, as in the case of 

 the well known functionally ovulate strobili of Cycadeoidea 



