338 



STUDIES IN FOSSIL BOTANY 



laminae wholly suppressed, cannot yet be determined. 

 The analogy of Zygopteris and Botryopteris, however, 

 speaks strongly for the former hypothesis. 



The sporangia are nearly spherical sacs, about 

 .7 mm. in diameter, with a wall several cells thick and 

 the outermost layer strongly differentiated. There is 

 no annulus, but a well-marked stomium at the end 



Fig. 127. — Stauropteris oldhamia. Three sporangia inserted terminally on ultimate 

 branches of the rachis. In A the stomium, st, is shown. B is cut tangentially. In 

 C, j> is the palisade-tissue of the rachi. The relatively large spores in C are probably 

 beginning to germinate. Cf. Fig. 128. X about 35. S. Coll. ; A, 2213 ; B, 2207 ; 

 C, 2219. R. S. 



opposite the stalk (Fig. 127, A) served for dehiscence. 

 Numerous spores of the tetrahedral type fill the 

 cavity. 



At the time when these sporangia were first dis- 

 covered, 1 the question was left open whether the plant 

 was a Fern or a Pteridosperm, for there was nothing to 

 show for certain whether the fructification represented 



1 Scott, "The Sporangia of Stauropteris oldkamia," New Phytologist, 

 vol. iv. 1905. 



