454 



STUDIES IN FOSSIL BOTANY 



Fig. 170. — Trigonocarpus Parkinson?. Diagrammatic median section in the plane of the 

 "wing" (Fig. 172). sa, sa?xottsta.\ /, its limiting layers; sc, sclerotesta ; n/i, 

 micropyle ; i.t, remains of "inner flesh"; sa.l<, sarcotestal bundles; f>.c, pollen- 

 chamber; p.c.b, its beak; s, septum at bottom of pollen-chamber; n.e, nucellar 

 epidermis ; n.t, nucellar tracheal system ; m.vi, membrane of megaspore ; t.d, 

 tracheal disc at chalaza ; ck-b, chalazal bundle, x about 3. From a drawing by 

 Mr. A. J. Maslen, F.L.S. 



