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FILICINE^ LEPTOSPORANGIAT/E 



313 



Fig. 173. — Onoclea struthiopteris. A, B, Germinating spores with the perinium re- 

 moved, X300; C, young prothallium, Xioo; D, E, older prothallia with two-sided 

 apical cell (;r), X300; F, small female prothallium seen from below, X25; G, 

 very young prothallium with the two outer spore-coats, X300; r, primary rhizoid; 

 ar, archegonia; p, perinium; ex, exospore. 



