14»'» (r. R. Wieland — Aiiurlcnn Fossil Ci/c<kIs. 



Fig. 6. 

 A 



a p x 



m e 



Fig. 6. Cycadeoidea turrita (?). Black Hills. 



h, 



n, 



m, 



e, 



il, 



-Longitudinal section of seed, x 15. 



pi, exterior covering or 

 layer " ; 



is, interseminal scales ; 



micropylar tube ending 

 slightly flanged style. 



blow off 



st, 



A.- 

 seed pedicel : 

 hilum; 



nucellar sack ; 

 megaspore membrane ; 

 embryo ; 

 interior layers of testa ; 



B. — Oblique section of four adjacent seeds, x 25. 

 n, nucellar sack ; m, megaspore membrane ; e, embryo. 

 In A all the basal portion of the section traverses thin " blow off " tissue, 

 which strongly thickens into a, five rib series at the shoulder, these ribs even 

 prolonging themselves tentacle-like into a sort of corona. The solid black 

 line represents the middle stone or sclerenchyma, the narrow blank space 

 between it and the nucellar sack the inner flesh, and the outer barred area 

 the exterior soft tissue or blow off layer. In this seed a rib is cut on the 

 upper side and a furrow is traversed on the lower side. Only in the micro- 

 pyle does the diagram fail of accuracy, as the middle sclerenchyma does not 

 give origin to all the micropylar wall. 



In B the nearly complete occupation of the megaspore membrane by the 

 embryo is seen to repeat itself normally. Occasionally in sections cutting 

 many seeds a third cotyledon is indicated. In the seed to the right no 

 embryo developed and the nucellar sack and megaspore membrane floated 

 to the center and collapsed, whence an extra line appears as the boundary 

 of the inner flesh. 



