186 Mr Sahni, On the branching of the Zygopteridean Leaf, etc. 



On the branching of the Zygopteridean Leaf, and its relation to 

 the probable Pinna-nature of Gyropteris sinuosa, Goeppert. By 

 B. Sahni, M.A., Emmanuel College. (Communicated by Professor 

 Seward.) 



[Read 20 May 1918.] 



( 1 ) The supposed quadriseriate " pinnae " of forms like Staurop- 

 teris and Metaclepsydi^opsis are tertiary raches, the vascular strands 

 of the secondary raches (pinna-trace-bar, Gordon) being completely 

 embedded in the cortex of the primary rachis. All Zygopterideae 

 therefore have a single row of pinnae on each side of the leaf. 

 (2) This revives the suggestion that Gyropteris sinuosa Goepp. is 

 a free secondary rachis of a form like Metaclepsydropsis. (3) The 

 genus Glepsydropsis should include Ankyropteris because: a. A 

 fossil described in 1915 (Mrs Osborn, Brit. Ass. Rep., p. 727) com- 

 bines the leaf-trace of Glepsydropsis with the stem of Ankyropteris, 

 the leaf-trace in both arising as a closed ring. h. In G. antiqua 

 Ung. also the leaf-trace arose similarly, as shown by a section 

 figured by Bertrand {Progressus 1912, fig. 21, p. 228) in which a 

 row of small tracheides connecting the inner ends of the peripheral 

 loops represents those lining the ring before it became clepsydroid 

 by median constriction. 



3 



The Structure o/Tmesipteris Vieillardi i)aw^. By B. Sahni, M.A., 

 Emmanuel College. (Communicated by Professor Seward.) 



[Read 20 May 1918.] 



The most primitive (least reduced) of the Psilotales. Specifically 

 distinct from T. tannensis in (1) erect terrestrial habit, (2) distinct 

 vascular supply to scale-leaves, (3) medullary xylem in lower part 

 of aerial stem. 



On Acmopyle, a Monotypic New Galedonian Podocarp. By 

 B. Sahni, M.A., Emmanuel College. (Commimicated by Professor 

 Seward.) 



[Read 20 May 1918.] 



Indistinguishable ivova. Podocar pus in habit, vegetative anatomy, 

 drupaceous seed, megaspore-membrane, young embryo, male cone, 

 stamen, two-winged pollen and probably male gametophyte. Chief 

 differences: (1) seed nearly erect; (2) epimatium nowhere fi"ee from 

 integument, even partaking in formation of micropyle; (3) outer 

 flesh with a continuous tracheal mantle covering the basal two-thirds 

 of the stone. 



