128 The Ohio Naturalist. [Vol. VII, No. 6, 



Fig. 1. Incipient sporangiophore showing cell which will cut off the 

 first cell of the sporangium. 



Fig. 2. Young sporangiophore showing periclinal division and first 

 anticlinal division perpendicular to a radius of the sporangiophore. 



Fig. 3. Tangential view of a young sporangiophore in which the 

 division of the first cell is radial. 



Fig. 4. Radial view of four-celled stage of young sporanigum, all 

 divisions having been anticlinal. 



Fig. 5. Radial view of six-celled stage of broad, rounded sporangium 

 second division periclinal. 



Figs. 6, 7. Radial views of six- and eight-celled stages of long. 

 slender sporangia. 



Fig. 8. Cross section of sporangium the same stage as Fig. 7 from 

 an adjoining sporangiophore. 



Figs. 9, 10. Radial sections of long, slender sporangia showing five 

 and seven cells respectively. 



Fig. 11. Longitudinal section of sporangium of the same type as 

 Fig. 10 and from an adjacent sporangiophore, cut tangential to the 

 strobilus. 



Fig. 12. Later stage in the development of a long, slender sporan- 

 gium; tapetum not yet differentiated. 



Fig. 13. Section of long, slender sporangium, showing formation of 

 tapetal layer; five outer cells slightly differentiated from the sporogenous 

 tissue will form wall. 



Fig. 14. Early stage in development of broad, rounded sporangium; 

 the second division was probably periclinal. 



Figs. 15, 16. Later stages in development of broad, rounded spo- 

 rangia; the heavy lines indicate the position of the first periclinal division. 



Fig. 17. Broad rounded sporangium, the tapetum beginning to 

 form; the heavy line indicates tte position of the first periclinal wall. 



Fig. IS. Later stage in development of broad, rounded sporangium, 

 the tapetum and wall differentiated and position of first periclinal division 

 indicated by heavy line. 



Fig. 10. Sporocyte stage of long, slender sporangium; the heavy 

 line shows position of early anticlinal division. 



Fig. 20. Section of older sporangium showing disintegrating 

 sporocytes. 



Date of Publication of March Number, April 18, 1907. 



