Mr Gordon, On a new species of Physostoma, etc. 395 



On a new species of Physostoma from the Lower Carboniferous 

 Rocks of Pettycur (Fife). By W. T. Gordon, M.A., B.Sc, Falconer 

 Fellow of Edinburgh University, and Advanced Student Exhibi- 

 tioner of Emmanuel College. (Communicated by Mr E. A. Newell 

 Arber.) 



[Bead 7 Tebruary 1910.] 



Among the rarer petrifactions of plant-remains occurring in 

 the Calciferous Sandstone Rocks at Pettycur are seed-like bodies 

 of various kinds. Perhaps the commonest example is Lepido- 

 carpon wildianuni, Scott*, while occasionally the pteridospermous 

 fructification — Gonostoma ovale, Williamson "f*, is also met with. 

 Under the name Conostoma interinediaX Williamson also placed 

 what are probably elongated specimens of G. ovale. These two 

 seed bodies are very distinct, for Gonostoma has a funnel-like 

 micropyle, whereas Lepidocarpon has no true micropyle. The 

 megaspore in the latter was exposed to the exterior by means 

 of a slit-like aperture between two enveloping outgrowths from 

 the sporophyll. 



Last year Prof. 01iver§ published his work on Physostoma 

 elegans, and showed that in that genus the apex of the seed 

 consisted of closely adpressed, free, tentacular processes; the 

 micropyle was thus capable of great enlargement. 



In the same paper he refers to C. ovale as being probably the 

 seed of Heterangium grievii, Williamson. The only evidence 

 however is association. Recently, while examining a new species 

 of Heterangium from Pettycur, I discovered several specimens of 

 C. ovale, and among them what appears to be a new and distinct 

 seed. The specimen had been cut through in an oblique tan- 

 gential direction, but by careful preparation I was able to get 

 one of the sections more nearly radial. One section is through 

 the micropylar orifice and the other passes through the chalaza. 



General Structure. 



The seed is radially symmetrical and is considerably larger 

 than G. ovale. The following table gives the dimensions of the 

 new seed and those of G. ovale. 



* Scott, Phil. Trans. Roy. Soc. B. Vol. cxciv. 1901, p. 291, 



t Williamson, Ibid. Vol. clxvii. 1877, p. 243. J Ibid. p. 246. 



§ Oliver, Ann. Bot. Vol. xxin. 1909, p. 73. 



