278 



STUDIES IN FOSSIL BOTANY 



differences in detail. In Kaulfussia the interior of the 

 synangium is hollowed out into a cup, into which the 

 sporangia open, dehiscence taking place on the inner 



Fig. 108. — Ptychocarjms unitus. Fructification. A. Part of a fertile pinnule (lower sur- 

 face), showing numerous synangia. R. Synangia in side-view. A and B X about 6. 

 After Grand'Eury. C. A synangium, in section parallel to the surface of the leaf, 

 showing seven confluent sporangia, a, bundle of receptacle ; b, its parenchyma ; c 

 tapetum ; d, spores ; c,f, common envelope of synangium. X about 60. After Renault. 



face of each sporangium. In the fossil genus there is 

 no central depression, and, as the entire synangium 

 was embedded in a continuous enveloping tissue, de- 

 hiscence could only have taken place at the apex. 



