VIII 



MARATTIALES 



297 



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

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

 but is really not essentially different from that in Kaulfiissia 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. 



Fig. i68.—Archang{opteris 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 Dancra, 7500 for Kanlfussia, 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 



