IG1 



On the Microsporangia of the Pteridosperms. 



By Robert Kidston, F.E.S. L. and R, F.G.S. 

 (Received November 15, — Read December 14, 1905.) 

 (Abstract.) 



The first point considered is the question of the identity of Lyginodcndron 

 Oidhamium and Sphenopteris Honinghausi, Brongt. Although this seems to 

 be generally accepted, it has not, as far as the author knows, ever been 

 demonstrated and from continental botanists a clear proof of their identity 

 may be justly demanded. The form, nervation, mode of attachment of the 

 sterile pinnules, the presence of spines on the pinnules and stems and the 

 sclerenchymatous net-like bands in the outer cortex are shown to be similar in 

 both, and further, that as a. petrifaction, Lyginodcndron Oidhamium on the 

 one hand, and as an impression, Sphcn. (Grossothcca) Honinghavsi on the 

 other, each in their respective condition, are the only two plants occurring on 

 the same horizon what each possess all these characters. 



The structure of the microsporangia of Sphcn. (Crossotheca) Honinghausi is 

 then described in detail, of which a preliminary account has already been 

 given.* This is followed by a description of the microsporangia of Grossothcca 

 Hughcsiana, n. sp., which possesses all the essential characters of the 

 microsporangia of C. Honinghavsi, differing only in its larger size and the 

 limb of the fertile pinnules being cordate, not oval, as in C. Honinghausi. 



The last part of the paper deals with the affinities of the Gycadofiliccs. 

 Beginning with the Upper Devonian, where the first satisfactory evidence of 

 the occurrence of " ferns " or " fern-like " plants is found, the fructification of 

 Archaeopteris is discussed and the conclusion arrived at that it agrees much 

 more with microsporangia than with true fern sporangia. The " ferns " of the 

 Culm are next considered, where the only evidence of " ferns " is found in the 

 occurrence of a few sporangia with an annulus of more than one row of cells. 

 The presence of the Cycadofiliccs on this horizon is very conspicuous ; the 

 Botryopteridcai also occur if one is justified in regarding Zygopteris as their 

 petioles. The annulate sporangia from this horizon are regarded as being- 

 more probably related to the Botryop>teridece than to the true ferns. 



The "ferns" or "fern-like" plants of the Upper Carboniferous are next 

 reviewed. In the Lanarhian scries or lowest division of the Upper Carbon- 

 iferous, which includes the Halifax hard bed — it is pointed out, that though 



* ' Roy. Soc. Proc.,' vol. B. 76, p. 358, 1905. 



