[ i3r J 



IX. 



THE OCOUREENOE OP ARCHMOPTEUIS TSCSEBMAKI, Stur., 



AND OF OTHER SPECIES OF AECH^OPTERIS 



IN IRELAND. 



By T. JOHNSON, D.Sc, F.L.S., 

 Professor of Botany iu the Royal College of Science for Ireland. 



(Plates VIL & VIII.) 

 [Read, March 28. Ordered for Publication, April 11. Published June 28, 1911. 



Archseopteris Tschermaki, Stur. 



The part of the frond preserved is simply pinnate, Rhaeopteris-like, 10 cm. 

 long and 2"5 cm. broad. The rachis shows along its central part a distinct 

 rectangular reticulum, as if it were divided up by transverse and vertical 

 strise into somewhat ^tuberoled minute segments. This sculpturing is con- 

 tinued into the midrib of the piunse. It looks like a blistered, cracked 

 surface ; but is apparently a natural feature, comparable to that seen by 

 Nathorst in Archceopteris fimbriata Natli., and that by Heer in Cardiopteris 

 frondosa, Gopp. 



Pinna 2'5-4 cm. long, sessile, forming an acute angle with the primary 

 rachis ; oblong in outline, with a distinct midrib ; the lamina with the sub- 

 parallel, dichotomous, or forked venation of the genus Arohseopteris; more 

 or less lobed, with slightly toothed edge, each tooth having three bundles 

 ending in it; the lowest pinna more deeply lobed. 



Sjiorangia. — At one point towards the apex are two fertile segments or 

 sporophyllules, each with its row of stalked sporang ia, like those of A. 

 hibernica. 



Archceopteris Tschermaki, Stur, suggests a connection of the genus 

 Archseopteris with the genus Rhacopteris, Schimp. of the Culm and Carboni- 

 ferous. Stur regarded the latter genus as a representative in the Culm of 

 the OphioglossaccEB, and saw in B. paniculifera, Stur, a now disputed type of 

 the modern Botrychium. 



SOIENT. PROC. E.D.S., VOL. Xm., NO. IX. X 



