104 A TEXT-BOOK OF BOTANY. 



In addition, sporophylls (spore-bearing leaves) are formed at 

 the ends of the young shoots or in the axils of more mature ones 



FIG. 65. A piece of slate from the coal formation in Shenandoah, Pennsylvania, showing 

 a fossil fern which is probably a species of Neuropteris. 



(Fig. 69). These are compactly arranged, forming cones or stro- 

 bili which are always of two kinds and borne on different twigs 

 of the same plant or on different plants. The staminate cones, 



