vin MARATTIALES 297 



shrinking of the cells on either side of the opening slit. The 

 latter in Dancca is short, and finally appears like a circular pore, 

 but is really not essentially different from that in Kaulfussia and 

 Marattia. In the latter there is a mechanical tissue which 

 causes the two valves of the synangium to gape widely at ma- 

 turity, and the dehiscence of the individual loculi is effected by 



A 



c. 



PIG. 168. Archangiopteris Henryi. A, Entire sterile leaf, reduced; B, base of stipe, 

 showing the stipules; C, part of a fertile pinna, of the natural size. (After 

 Christ & Giesenhagen.) 



the contraction of thinner walled cells surrounded by firmer 

 tissue. 



The number of spores produced in each loculus is approx- 

 imately 1750 for Dancca, 7500 for Kaulfussia, 2500 for Marat- 

 tia, and 1450 for Angiopteris. 



Bower's account and figures of Angiopteris differ from the 

 specimens examined by the writer in the greater thickness of 



